Image copyright Henry Vaughan Image caption Police in Chalgrove Road, Tottenham, where a 17-year old girl was shot dead in a drive-by attack

Claim: London has overtaken New York for murders for the first time in modern history after a surge in knife crime across the capital.

Verdict: A selective use of statistics from the start of 2018 appears to bear this out - but the reality is that New York still appears to be more violent than London.

Criminologists and police chiefs love studying the differences and similarities in violence between big cities because the huge amounts of data can give clues as to what works best to keep people safe.

There has been no end of comparisons down the decades of London and New York because, on the face of things, the cities are broadly comparable.

They're both cosmopolitan "world cities" with broadly similar populations of more than 8 million people. They also have big gaps between rich and poor inhabitants.

But there has always been one significant difference: the crime rate. So this weekend's report in the Sunday Times, which could be interpreted as suggesting that London was now more dangerous than New York, needs some unpicking. And, as you may have come to expect from BBC Reality Check, the truth is a little more complex.

Image copyright Getty Images Image caption New York police have opened 50 murder files so far this year - this compares with 48 in London

According to the newspaper, London overtook New York's "murder rate" in February "as the capital endured a dramatic surge in knife crime".

That is true. The New York Police Department dealt with 11 homicides in February - while London's Metropolitan Police opened investigations into 15 deaths. And in March, there were 22 killings in London and one fewer on the other side of the Atlantic.

But that grim month-by-month tally is not quite the whole story.

The one thing that's always true about statistics is that there will be blips - sudden rises or falls in the data. These two high months for London could ultimately turn out to be outliers.

We don't yet know. But older data shows why we should be cautious.

In January, for example, the Met investigated eight murders in London. The NYPD looked into 18 killings.

And that means that while Scotland Yard has opened 48 homicide inquiries so far this year, New York has in fact opened 50 murder files.

Looking at 2017, the homicide rate per 100,000 population stood at 1.2 in London and 3.4 in New York.

While the difference between the two cities has definitely narrowed - the trend is far from fixed. And even older figures are also quite revealing.

In 2007, New York witnessed 496 homicides. That was three times more than in London. Last year, the American city suffered 292 killings and London 130.

The rate of killings so far this year in London is higher than it was during the same period last year. The fatalities include five shootings and 31 stabbings.

Nine of those killed were teenagers and crimes involving knives and sharp instruments across England and Wales are at their highest level since 2011.

Why the rate is going up in London, so far this year, is unclear. There's a push for police to stop and search more suspects for weapons after a big fall in the use of the power since 2010. But New York police have also reduced their use of similar powers over the same period - and their murder rate has fallen.

New York is definitely a much safer place than in 1990 when there were 2,262 murders. But it's not remotely clear yet that London is becoming more murderous than its American cousin.

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