Matt Ashby

@mattashby

I help people use data to reduce crime. Associate Professor, Crime Science, UCL. Former police officer. 🌐: mattashby.com

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Matt Ashby@mattashby· 4h

The reason for the huge difference in fresh water usage is specifically because in the UK cows are almost always eating grass, whereas in the US they’re usually eating feed that’s been irrigated.

This is relatively low, because most beef consumed in the UK is fed on rain-fed grass and crops. Production systems in the US, on the other hand, that rely on irrigated feed may consume almost 2,000 litres per kg. This is blue water that has been diverted from rivers and aquifers.

Matt Ashby@mattashby· 3d

Two absolutely fantastic experiences (illustrated with two bad photos) in one evening. Both completely brilliant.

Gustavo Dudamel conducting the Los Angeles Philharmonic in the Royal Albert Hall

Matt Ashby@mattashby· 6d

Well this never gets old!

View looking upward at the domed ceiling of the Royal Albert Hall for the BBC Proms, illuminated in vivid red and purple, with large spherical acoustic diffusers suspended around a central circular lighting rig. Stage lighting and BBC Proms signs are visible at the bottom of the image.

Matt Ashby@mattashby· 16d

… and more research symposia should finish with a hike in the sunshine, too!

A group of eight people walk in single file along a narrow path across open moorland under a clear blue sky. Tall grasses and purple heather line the path, with the walkers photographed from behind as they head towards the distant horizon. The late afternoon sunlight casts warm light across the landscape, highlighting the textures of the grasses and the wide, open expanse of the moor.

View from a hillside overlooking a large historic stone building surrounded by mature trees, with a smaller stone structure in the foreground. Beyond the estate, a patchwork of fields, woodland and scattered villages stretches across a broad valley towards rolling hills on the horizon. The scene is lit by bright sunshine beneath a clear blue sky, creating a layered landscape of green woodland and golden farmland.

Matt Ashby@mattashby· 16d

More research symposia should take place in sunny gardens. Thanks @jpinasanchez.eurosky.social and @ianloader.bsky.social for organising!

A group of people sitting on the grass in front of a screen of bushes. The people are looking at a man who is standing and speaking to them. The people are dressed casually and the scene is bathed in sunlight.

Matt Ashby@mattashby· 22d

If you’ve never walked across a slice of a city to get a real feel for the place, I can’t recommend it highly enough. (Assuming you’re able to walk, of course.) Some sights from various wanders in London:

An urban canal just after sunset, with the orange sky reflected in the still water. There are trees either side of the canal and narrow boats tied up on one bank.

The Centrepoint building in central London bathed in evening sunlight.

A neoclassical building lit up with coloured lights.

The skyscrapers of Canary Wharf behind the neoclassical buildings of the Old Naval College in Greenwich.

Matt Ashby@mattashby· 27d

93% of people living in Greater Manchester say they live in the North. yougov.com/en-gb/articl...

Map of England showing the percentage of adults in each ceremonial county who say they live in “the North of England”, based on a YouGov Profiles survey of 45,856 adults in England conducted in October 2025. Counties are shaded from light grey (0–10%) through progressively darker pinks and reds to dark maroon (81% or more).

The map shows a clear north–south gradient. All counties in the far north of England are dark red or maroon, indicating that more than 70% of residents, and in several counties more than 80%, identify as living in the North. High levels extend across Northumberland, Tyne and Wear, County Durham, Cumbria, North and West Yorkshire, Greater Manchester, Merseyside and much of Lancashire.

The strongest transition occurs across the Midlands. Northern parts of Derbyshire, Nottinghamshire, Staffordshire and Shropshire have at least half of residents identifying as living in the North, while neighbouring counties further south have substantially lower proportions. Counties such as Cheshire, Derbyshire, Nottinghamshire, Staffordshire and Shropshire form the main boundary zone, with values generally between 41% and 70%.

South of this transition, most counties are pale pink or light grey, indicating that fewer than 30% of residents identify as living in the North, with many southern counties below 10%. An annotation highlights that “At least half of those who live in the northern parts of Derbyshire, Nottinghamshire, Shropshire and Staffordshire say they live in the North.” The source is YouGov Profiles, October 2025.

Matt Ashby@mattashby· Jun 29

People in London support police using AI for a wide variety of tasks including translation, identifying high-risk repeat offenders and prioritising deployment. They do feel it’s important to have a human in the loop, though. www.police-foundation.org.uk/news/new-res...

Alt text:

Horizontal stacked bar chart titled “Support and opposition to police uses of AI”. Respondents were asked: “To what extent would you support or oppose the police using AI for each of the following purposes?” Each bar is divided into five categories: strongly oppose (dark burgundy), somewhat oppose (pink), neither (grey), somewhat support (light blue), and strongly support (green). Support is highest for fast translation for non-English speakers (66% support) and safeguarding vulnerable people faster (64% support, 17% neutral, 16% oppose). Around six in ten support using AI for predicting where police resources are needed (63%), linking related crimes (64%), identifying serious or repeat offenders and victims (63%), assisting with cold cases (62%), detecting internal police misconduct (62%), automating record-keeping and administration (61%), and managing deployments during busy periods (57%). Support is weaker for reducing civilian staff to fund frontline policing (45% support, 25% neutral, 26% oppose), predicting which individuals will offend (44% support, 24% neutral, 27% oppose), and assisting judges and jurors (43% support, 23% neutral, 30% oppose), the latter attracting the greatest opposition. Overall, support exceeds opposition for every proposed use.

Matt Ashby@mattashby· Jun 26

Opinions from towns beginning with other letters are presumably also available! 😁

Part of a presentation slide saying “Focus groups: Leeds, Lancaster, Lichfield, London”

Matt Ashby@mattashby· Jun 20

England’s latest sunset of the year (more or less). Although the sun is setting behind hills that are in Scotland! 📍 Allonby, Cumbria

Sunset over a broad tidal shoreline at low tide. In the foreground, wet sand and scattered dark pebbles reflect the warm light of the setting sun. Bands of exposed mudflats and shallow pools stretch across the middle distance, creating horizontal layers between the beach and the sea. The sun sits just above the horizon near the centre of the image, casting a narrow orange reflection across the water and wet sand. Beyond the sea, a range of low, dark hills and mountains forms a silhouette against the sky. The sky transitions from bright orange near the horizon to pale peach higher up, with only a few small clouds visible. The overall scene is calm and expansive, with strong reflections and contrasting dark shoreline textures.

Matt Ashby@mattashby· Jun 13

Romanian was the third most spoken language in England after English and Polish in 2021, and it wasn’t far behind Polish. I wouldn’t be surprised if Romanian is above Polish in the next census, given how well the Polish economy is doing. www.ons.gov.uk/peoplepopula...

Slope chart comparing the ten most commonly spoken main languages other than English in England and Wales in the 2011 and 2021 censuses. Languages are ranked by position in the top ten, with lines showing changes in rank between years. Polish remained the most common language in both years, with 612,000 speakers in 2021. Romanian showed the largest rise, moving from outside the 2011 top ten to second place in 2021 with 472,000 speakers. Panjabi and Urdu ranked third and fourth in 2021, followed by Portuguese, Spanish, Arabic, Bengali, Gujarati and Italian. Several languages that were in the 2011 top ten fell in rank by 2021, while Portuguese, Spanish, Romanian and Italian moved into the top ten. The chart emphasises changes in ranking rather than changes in the number of speakers, with connecting lines linking each language’s position in 2011 and 2021.

Matt Ashby@mattashby· Jun 12

I've been seeing this map all week across social media, but quite a few things about it are wrong (no Southwark, two Bexleys) that suggest it's been AI generated without checking the details. So I created a version based on the actual census data:

Map of Greater London showing the most common non-English language spoken in each borough, based on the 2021 Census. English is the most common language everywhere, so the map displays the second most common language. Distinct colours indicate different languages. Romanian dominates much of outer north-east and east London, including Barnet, Harrow, Waltham Forest, Redbridge, Barking and Dagenham, Havering and Bexley. Turkish is most common in Enfield, Haringey and Hackney. Spanish is most common in several central and south-west boroughs, including Islington, Wandsworth, Lambeth, Lewisham, Richmond, Southwark and the City of London. Panjabi is most common in Hillingdon, Ealing and Hounslow. Bengali is most common in Tower Hamlets and Newham. Other boroughs show French (Camden, Hammersmith and Fulham, Kensington and Chelsea), Gujarati (Brent), Arabic (Westminster), Nepali (Greenwich), Polish (Merton and Croydon), Portuguese (Bromley) and Tamil (Kingston and Sutton).

Matt Ashby@mattashby· Jun 9

At the point where people are setting fire to vehicles, those people are either rioters or arsonists, not protestors.

Screenshot of a social media post from Sky News. The post headline reads, “Vehicles set alight in Belfast as protesters take to the streets.” Below the headline is a split image showing two scenes of vehicles on fire. On the left, a large vehicle burns intensely on a city street, with bright orange flames and thick black smoke rising high above nearby buildings. On the right, another vehicle burns in a residential area, surrounded by a crowd of people gathered nearby. The linked article preview repeats the headline and mentions a man charged with attempted murder after a knife attack.

Matt Ashby@mattashby· Jun 9

My UCL Crime Science colleague Jyoti Belur has set herself quite the challenge to answer this question in her professorial inaugural lecture this evening!

A presentation slide with the text “The central question: How can police organisations be ethical, equitable and efficient at the same time?”

Matt Ashby@mattashby· May 7

A really useful framework for police leaders to think through the issues associated with adopting a new technology, written by my colleagues Shane Johnson and Kate Bowers. More detail in this paper: doi.org/10.1111/1467...

The Elements of CRIMEFACE
Crime reduction/detection outcomes
Reactionary outcomes other than crime
Implementation considerations
Misuses/potential backfire effects
Economics
Future proof-ability
Applicability
Contextual differences
Ethical considerations and sustainability

Public Trust in Digital Technology: 'CRIME’

CRIME
Does or is the technology likely to reduce crime or improve its detection?

MISUSES
What are the likely reactionary outcomes:
1. Perceptions of legitimacy
(will the public accept it)?
2. Public Trust (will the public engage with it?
3. Explainability (can the public easily understand it?

IMPLEMENTATION
How easy is integration with current systems?
What are the knowledge expertise requirements?
Does it need a security protocol change? Cultural or technological?

MISUSE
What is the potential for misuse or backfire effects?

ECONOMICS
What is the likely value for money and cost-effectiveness?
What is the likely return on investment?

Public Trust in Digital Technology: 'FACE'

FUTURE USE
Will it stay current or go obsolete quickly?
Will future use or updates be costly?

APPLICABILITY
Are there clear mechanisms for crime reduction and detection?
Are there clear mechanisms for reactionary outcomes such as public trust?
Is the technology relevant to multiple crime scenarios and crime types? How adaptable is it across problems?

CONTEXT
Is effective operation highly context dependent?
Might contextual differences affect implementation, crime outcome and/or public reactions?

ETHICS
What are the ethical considerations including:
- Transparency
- Proportionality
- Is it non-discriminatory and unbiased?
- Does it comply with DPA?
- Are the ethical
implications evaluated?
- Environmental impact including sustainability and carbon costs.

Matt Ashby@mattashby· Apr 27

@scottkeay.bsky.social 1h 41min!? 😳 This had better be good.

A podcast listing showing an episode of the podcast Analyst Talk featuring Scott Keay is 1 hour 41 minutes long

Matt Ashby@mattashby· Apr 26

Really nice atmosphere at today’s Champions League semi-final at the Emirates. Going to a women’s top-flight match is just such a nicer experience than going to a men’s game. If you’ve not tried it, it’s a great afternoon out!

A crowd at a football match, with a banner saying UEFA Women’s Champions League

Matt Ashby@mattashby· Apr 23

Former chief Dennis O’Connor is now passionately emphasising the importance of signal crimes (crimes that might be quite minor but are highly visible) to public perceptions of safety and confidence in policing.

A conference panel including Professor Emeritus Gloria Laycock, UCL Jill Dando Institute of Security and Crime Science, Matt Twist, Metropolitan Police Service Assistant Commissioner, Sir Denis O'Connor, former Chief Inspector of Constabulary, chaired by Dame Sara Thornton, Chair of Trustees, The Police Foundation

Matt Ashby@mattashby· Apr 23

Today @rusi.bsky.social is hosting a discussion on 30 years of broken windows policing in the UK. Very interesting to hear from David Blunkett on the difficulties he faced in convincing police chiefs they should focus on prevention of everyday crime!

Former Home Secretary David Blunkett, former New York City Police Commissioner Bill Bratton and Director of the Police Foundation Blair Gibbs in a panel discussion on a stage

Matt Ashby@mattashby· Apr 21

Gen-Z teens are getting arrested much less often than Millennials were, while Millennials are still getting arrested as they get older (🇺🇸), so the typical person arrested for some crimes is now in their 40s rather than the young-offender stereotype. crimeforecast.substack.com/p/the-age-cr...

Line chart showing male larceny-theft arrest rates per 100,000 by age group for 2005, 2015, and 2025. Across all three years, arrest rates are highest among teenagers and young adults, then decline steadily with age, but the shape and level of the curve change over time.

In 2005, rates peak sharply in the late teens (around ages 17–19) at very high levels (roughly 1,400–1,500), then drop quickly through the 20s and continue declining into older ages. In 2015, the pattern is similar but less extreme: the teenage peak is lower (around 1,100–1,200), and rates in the 20s are relatively higher than in 2005, producing a more gradual decline.

By 2025, the distribution is flatter and shifted toward older ages. The teenage peak is much lower (around 400), while rates in the late 20s to mid-30s are comparable to or slightly higher than those for teenagers, creating a broad plateau rather than a sharp peak. From about age 40 onward, all three years show similar declining patterns, with relatively small differences by older age. Overall, arrest rates have fallen substantially among younger males and become more evenly distributed across early and middle adulthood.

Matt Ashby@mattashby· Apr 16

Loads of interesting findings in a new report on how police (🏴󠁧󠁢󠁥󠁮󠁧󠁿/🏴󠁧󠁢󠁷󠁬󠁳󠁿) spend their time, including that police spend more time investigating violent crime than any other crime type, and they spend almost no time investigating people's social-media posts. Some other highlights …

Figure 3 bar chart showing proportion of time spent on specific crime incident activities by type. “Violence with injury” is highest at 14.7%, followed by “Violence without injury” (8.3%) and “Other sexual offences” (8.1%). Mid-range categories include rape (7.2%), homicide (6.4%), trafficking of drugs (5.6%), and vehicle offences (4.8%). Several categories cluster around 3–4%, including stalking and harassment, public order offences, and fraud/forgery. Lower proportions include possession of weapons (2.7%), shoplifting (2.4%), robbery (2.2%), and burglary business/community (1.5%). The smallest shares are theft from the person (0.9%), arson (0.7%), and bicycle theft (0.2%). Overall, time is concentrated in violent offences.

Figure 5 bar chart showing proportion of time spent on PSW incident activities by type. “Missing person” dominates at 16.0%, followed by “Concern for safety” (14.2%) and “Police-generated resource activity” (12.2%). Next are ASB/nuisance (5.6%), unknown (5.5%), and domestic incidents (4.8%). Many categories fall between 2–4%, including messages, welfare checks, road-related offences, and collisions. Smaller categories include suspicious circumstances (1.8%), personal incidents (1.7%), highway disruption (1.3%), and contact records (1.2%). Very low proportions (under 1%) include firearms, environmental incidents, civil disputes, protests, lost property, hoax calls, alarms, and others, with several near 0%. Time is heavily concentrated in safeguarding-related incidents.

Matt Ashby@mattashby· Apr 6

A tranquil rural scene shows a narrow stream flowing through a neatly maintained garden beside a cottage. On the left, a blue-painted house with a wooden door and chimney sits behind a small gravel area, where a bench and a British flag are visible. The garden features bright green grass edged with spring flowers, including clusters of yellow daffodils. A tall, conical shrub stands near the house, while a weeping willow drapes its branches over the water. The stream runs gently over stones toward a small stone bridge in the background, with trees and hedges lining both banks under a cloudy sky.

Matt Ashby@mattashby· Apr 1

While medical treatment has definitely improved, it can’t be the main explanation for the homicide drop because we know that non-fatal serious violence has also dropped at the same time.

Three side-by-side line charts show long-term trends in non-sexual violent crime in England and Wales from 1993 to 2023, measured as crimes per 1,000 people aged 16+. Categories are serious injury, minor injury, and no injury. All three series decline substantially over time. Serious injury falls steadily from the late 1990s to a low level by 2023. Minor injury shows a sharp drop in the early 2000s, a brief plateau around 2010, then further decline. No injury starts highest, decreases gradually, with a small mid-period flattening, then continues downward. Data are three-year moving averages from the Crime Survey for England and Wales.

Matt Ashby@mattashby· Mar 23

There are often stories of UK universities treating their staff badly (in some cases apparently vindictively so), so it's good to see @ucl.ac.uk introducing better paid parental leave across different circumstances.

We are very pleased to announce we will:
Increase paid paternity/partner's leave from 4 to 12 weeks from 1 May this year.
Increase paid maternity and adoption leave from 18 weeks to 22 weeks from 1 May this year to ensure all parents have increased time off at this important time with less financial worry.
Introduce a paid leave period of two weeks for parents who experience pregnancy loss before 24 weeks of pregnancy (a week of paid leave to partners will also be provided).
Partner with an external provider to introduce backup care for all staff where their regular caring provision breaks down last minute, disrupting their normal working pattern.

Matt Ashby@mattashby· Mar 14

📍 Great Longstone

Sunbeams stream through thick clouds in a bright sky, illuminating a rural landscape with the silhouette of a lone leafless tree on the horizon.

Matt Ashby@mattashby· Mar 7

If the title of this book is to be believed, forensics must be easier to learn than I’d thought.

The cover of a book titled (in German) ‘Forensics in 30 seconds: crime investigation through science’

Matt Ashby@mattashby· Feb 26

Well this looks like a pretty big editorial failure: a book review in the Journal of Criminal Justice Education retracted because it “contains such extensive inaccuracies that it neither describes nor evaluates the book it claims to review”. www.tandfonline.com/doi/abs/10.1...

We, the Editor and Publishers of Journal of Criminal Justice Education, have retracted the following book review:

Kresnanda Annas, G. (2025). Organising White-Collar and Corporate Crimes: By Nicholas Lord and Michael Levi, New York: Routledge, Published 2025, 218 p., 19 B/W Illustrations, £35.99 (eBook), ISBN: 9781315100227. Journal of Criminal Justice Education, 30 April 2025, DOI: 10.1080/10511253.2025.2500310.

Following publication, a third party raised concerns regarding the integrity of the review. Upon investigation and following correspondence with the author, the Journal and Publisher confirm that this book review contains such extensive inaccuracies that it neither describes nor evaluates the book it claims to review.

We have been informed in our decision-making by our own publicly available editorial policies and COPE guidelines.

The retracted book review will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

Matt Ashby@mattashby· Feb 11

Today mark‘s the 200th anniversary of the founding of UCL, London’s first university. Apparently, right from the start UCL was looked down on by some for being too egalitarian, because we admitted (male) students regardless of religion or background!

A large neoclassical stone building at night with the words UCL200 projected onto it

Matt Ashby@mattashby· Feb 7

Betteridge's law of headlines almost certainly applies. en.wikipedia.org/wiki/Betteri...

Betteridge's law of headlines is an adage that states: "Any headline that ends in a question mark can be answered by the word no." It is based on the assumption that if the publishers were confident that the answer was yes, they would have presented it as an assertion; by presenting it as a question, they are not accountable for whether it is correct or not.

Matt Ashby@mattashby· Feb 7

One advantage of the wet weather: waterfalls currently look amazing! 📍@nationaltrust.org.uk Aira Force