Steve, you are in for a treat. We've been on 10 RS tours, including Best of London, and have loved them all - and we were people who thought we'd never do a group tour!
Our BoL tour stayed at myhotelchelsea, which is quite nice, definitely upscale. (My DH and stayed in a less expensive, less luxurious hotel before and after the tour.) The rooms are very small, by American standards, but that is common in Europe. The breakfasts (included) were excellent.
Our guide was Roy, one of the best RS guides we've ever had. Our "local guide" was Gillian, who is also first rate.
The food on the included meals is good. Our first group meal was afternoon tea. I'm one of the ones who was less than satisfied with it, but that's only because I can't eat sweets. A few tiny sandwiches were included, but it was mostly sweets. We had a great pub lunch with the group, and a good Indian meal. The final group dinner was excellent. We never had fish and chips with the group, and I don't even remember the beef and potatoes that someone else mentioned.
Plenty of free time; your guide will offer suggestions for sightseeing on your own if you want them.
It's a super tour, and a good introduction to RS tours.