I think what OP meant was that Britan has the highest rate of violent crimes in the EU. This was all over the news a few years ago, and it's still fairly high, but it's important to note that the UK is very lax in what it considers "violent crime". Whether that's a good thing or not is another matter.

I think you read that wrong. That Britain has the worst violent crimes in the EU is definitively Britain's problem.

You should parse that sentence as "Britain has the highest occurrence of violent crime in the EU," which is very much our problem.

He means that Britain has the worst level of violent crimes of any country in the EU.

Worst != Worse