Hi Bee, and welcome to FT! I should also try your place next time I'm in London since I stay at the Hyatt Churchill on Portman Square, which looks about a 6 minute walk away. For some reason, I've rarely gotten north of Wigmore St when looking for a place to eat.
Do you get BOTH the fish and then the lamb for that price? I guess so, since it is billed as a 4 course meal. Looks like an interesting deal.