When I lived in London it was the Aberdeen Angus Steak House [0], never any customers despite being on the main thoroughfairs..
[0] https://www.telegraph.co.uk/foodanddrink/4813176/Who-goes-th...
Rather than money laundering or anything shady like that, I always assumed it was just a fiendishly well-designed tourist trap. The branding is perfectly pitched to make it somehow look both classy and cheap (which are exactly the two things you want and need as a tourist in London).