Advice/recommendations for London (marylebone/mayfair/fitzrovia) Wedding Reception Venue

Help! FH and I are searching for a venue to host wedding reception after our private ceremony at Marylebone Town Hall next summer. We’ll have around 50 guests - our nearest and dearest - and we need a venue where we can host a sit down dinner as well as dancing/dj later (perhaps venue would have 2 rooms/spaces). Have exhausted all I can think of. Most private dining rooms can’t fit 50. I’m searching for something fairly informal, but sophisticated. Ideally not a pub, nor a hotel event space. Happy for it to be a restaurant that we hire out. Anyone held/attended a reception after a ceremony in London that can recommend a venue? THANK YOU!!