Just a quick observation: since I last visited London two years ago, almost every business I've encountered has gone cashless. Coffee shops, pubs, the Transport Museum, all cards-only. In 2019, most of the smaller places preferred cash.
No real consequences, other than not needing to withdraw Sterling so far this trip. When I get home and sync up Quicken, I expect I'll have a little work, but again, not a biggie.