22 North Street in Clapham Old Town has a beautiful private room downstairs. Highly recommend it for a gathering, and the food and service are pretty special too. From memory it fits 8-10 people but maybe give them a call to check.

We had a brilliant dinner in a private room at 10 Cases. The wine was fantastic, and the staff took time to explain its provenance, and how it paired with the food.

http://10cases.co.uk/

http://www.medlarrestaurant.co.uk/private-room is very nice

I would recommend
Aqua Kyoto - Japanese restaurant and terrace bar in Argyll street, very close the the Palladium. An all private roomed restaurant and wonderful views outside for some air on the the terraces afterwards

Check out the Marsham Room at Shepherds in Westminster. It's a really interesting space and seats up to eight guests.

http://www.shepherdsrestaurant.co.uk

A friend had a 50th lunch at the Ivy Market Grill in Covent Garden in one of their private rooms which was fantastic, I don't know room capacities but think they have a few room sizes.

I believe the Square Meal website lets you search for restaurants with private rooms (and also by size, area, cuisine, price etc)

Hi all - I'm looking for a small semi private room in a restaurant in central London. It's for 8 - all trustees of a small charity. Needs to be a nice space, so that they can socialise and talk. Can anyone recommend a place? Or a site that locates such places? Thanks