They'll have a long way to go before outpacing London [0] but perhaps Brexit will have some value after all! I can't link to the primary source but Private Eye is one of the best oversights in the UK. The proprietor, Ian Hislop, was purportedly the most sued man in Britain at one point [1].
It's my understanding that the casino laundering scheme has been going on for decades but I can't imagine that'll go on forever. I'm not too sure where you go from there. I guess start a 'legitimate' cash business but I imagine there's much better ways.
[0] - https://www.thebureauinvestigates.com/stories/2012-08-09/lon...
[1] - https://www.independent.co.uk/news/people/profiles/ian-hislo... - "Since then, Hislop has become the most sued man in English legal history, though he says the rate of libel actions is slowing."