Now you can go "those high-earning landlord scum" as much as you want, but nobody in their right mind would say that it's better to have a situation in, say, small towns in the Northeastern England where rent is spectacularly low — but so is employment.
Look at what happened in 2008. Finance caught a cold and the entire global economy including Britain fell flat on it's back. Brexit has the potential to do far more damage over a much longer period of time, but mostly just to Britain. The knock on effect across the country isn't going to be pretty. But hey, if the rest of Britain decides they'd rather like to have a long drawn out recession just in order to stick it to the bankers then fine.
However London is a global cultural and trade hub entirely due to it's finance industry. Take that away and what does London or Britain have economically? Every single London resident would suffer from that from lower wages, fewer employment prospects and higher taxes. Property would be less valuable and so rents might fall, but so would earnings to pay for it with.
I fully expect a 'we should be making cars (or whatever) instead of running banks' type argument, but why is that a choice? Anything else we could do to make up for losing Finance we could do anyway. We had a 3 term Labour government. They were in power for 13 years. If anyone was going to dial back the clock and 'save' Britain by turning it into a low-wage, low value jobs-for-the-boys economy they had the chance. Killing finance first then wondering what to do instead is kind of the wrong way to go about something like that.
