Estimating the effect of Europe’s largest street party on crime in London

Matt Ashby
matthew.ashby@ucl.ac.uk

UCL Department of Security and Crime Science

“The level of knife-related violence, aggression towards emergency workers, and on-the-street debauchery … is a fundamental betrayal of Notting Hill Carnival’s heritage and origins” Rakib Ehsan in CapX

“A two-day festival at which a million folk are having a wild time should not be judged by the villainy of a few” – Brendan O’Neill in The Spectator

“I dread this event every year, it gets more violent each time. How many more officers have to get injured or innocent members of the public killed?” – The Police Federation

“It’s a UK success story. I hope a few more of the naysayers experience it, before hastily jumping on the bandwagon of criticism!” – Leroy Logan in The Guardian

Working out how much crime is attributable to Carnival

We can’t do a randomised controlled trial …

… so we try to get as close as possible

… using a difference-in-difference model with two-way fixed effects

Step 1: create a grid of small cells covering London

Step 1: create a grid of small cells covering London

Step 2: count crimes of each type in each cell on each day

… June–October 2013–2023

… 15,462 grid cells × 1,323 days = 20,456,000 cell–day observations per crime type

Step 3: estimate the baseline daily frequency of crime in each grid cell

to account for population, socio-economic factors, land use, bars, shops, etc.

Step 4: estimate the London-wide frequency of crime on each day

to account for long-term trends, seasonal effects, public holidays, weather, etc.

After we take all that into account

… we’re left with only variation specific to each grid cell on a particular day

… and if Carnival had an effect on crime

  • the difference in crime levels between Carnival and non-Carnival days in grid cells closer to Carnival
  • would be bigger than the difference between Carnival and non-Carnival days in grid cells further away from Carnival

So, how much crime is attributable to Carnival?

Additional crimes due to Carnival each year

Annual cost of additional crimes due to Carnival

crime type
estimated social cost (£)
estimated policing cost (£)
estimate 95% CI estimate 95% CI
criminal damage
personal robbery
sexual offences
theft from the person
violence with injury
violence without injury

Annual cost of additional crimes due to Carnival

crime type
estimated social cost (£)
estimated policing cost (£)
estimate 95% CI estimate 95% CI
criminal damage 34k 8k to 60k
personal robbery 687k 427k to 947k
sexual offences 552k 280k to 824k
theft from the person 418k 225k to 611k
violence with injury 3,091k 2,400k to 3,781k
violence without injury 540k 367k to 714k

Annual cost of additional crimes due to Carnival

crime type
estimated social cost (£)
estimated policing cost (£)
estimate 95% CI estimate 95% CI
criminal damage 34k 8k to 60k 5k 1k to 9k
personal robbery 687k 427k to 947k 106k 66k to 146k
sexual offences 552k 280k to 824k 94k 48k to 140k
theft from the person 418k 225k to 611k 219k 118k to 321k
violence with injury 3,091k 2,400k to 3,781k 295k 229k to 361k
violence without injury 540k 367k to 714k 36k 24k to 48k

Carnival vs London crime rates

crime type London rate2
rate per 100,000 in Carnival footprint, based on …1
2 million attendees 1 million attendees
bicycle theft
commercial burglary
criminal damage
personal robbery
residential burglary
sexual offences
theft from the person
vehicle theft
violence with injury
violence without injury
1 Assuming that on-average attendees spend 4 hours at Carnival (Movement Strategies 2017)
2 Based on crimes on non-Carnival days, July–October in 2013–23, and London population of 8.79 million

Carnival vs London crime rates

crime type London rate2
rate per 100,000 in Carnival footprint, based on …1
2 million attendees 1 million attendees
bicycle theft 0.7
commercial burglary 0.6
criminal damage 1.8
personal robbery 0.8
residential burglary 1.4
sexual offences 0.4
theft from the person 1.3
vehicle theft 3.1
violence with injury 2.2
violence without injury 3.8
1 Assuming that on-average attendees spend 4 hours at Carnival (Movement Strategies 2017)
2 Based on crimes on non-Carnival days, July–October in 2013–23, and London population of 8.79 million

Carnival vs London crime rates

crime type London rate2
rate per 100,000 in Carnival footprint, based on …1
2 million attendees 1 million attendees
bicycle theft 0.7 0.7 1.3
commercial burglary 0.6 0.5 1.1
criminal damage 1.8 7.0 14.0
personal robbery 0.8 18.0 36.0
residential burglary 1.4 1.7 3.5
sexual offences 0.4 9.3 18.5
theft from the person 1.3 106.2 212.4
vehicle theft 3.1 1.8 3.6
violence with injury 2.2 44.5 89.1
violence without injury 3.8 29.7 59.5
1 Assuming that on-average attendees spend 4 hours at Carnival (Movement Strategies 2017)
2 Based on crimes on non-Carnival days, July–October in 2013–23, and London population of 8.79 million

Conclusion

  • Carnival leads to a significant increase in criminal damage, personal robbery, residential burglary, sexual offences, theft from the person, and violence with and without injury
  • Many of these effects extend beyond the Carnival footprint
  • The social costs of these additional crimes is between £3.71m and £6.94m per year
  • The effect on overall crime in London is small

Thanks!

These slides
lesscrime.info/talk/eurocrim-2026/

Questions and comments
matthew.ashby@ucl.ac.uk