We had a party of 10 for 21 Club, and the experience was awesome. There was the Salvation Army there for Christmas caroling, which was an interesting experience. They went around to collect donations after. The menu was also pre-fixed.
For the first starter, I got the Lobster Bisque (4.5/5). Then I got the duck (3/5) - great sized portions, but nothing out of the ordinary. Then I had the tiramisu (4/5). Overall, the food quality was high. They were very courteous, professional, and quick.
The overall lunch took 2.5 hours, which was longer than expected, so keep that in mind.
I would come back for business meetings for sure. Super swanky with a jacket required. There is a lot of old money in here!