Venue for 3 year old party in London. Suggestions, please!

[schroedingersdodo]

DS1 will be 3 in May, and I'm looking for a nice venue for a party, where a few children can play and the adults can be a bit comfortable.

I live in NW3, so something local would be nice, but anywhere in London with good access to transport is fine.

One option I considered was the Golden Hinde (pirate ship on the Thames) but it's for children from 5 years - and a bit pricey. I would love something similar, but suitable for younger children.

Thanks!

Coram fields? You can hire the rooms there. I am considering it for my 4 year old's party.

I've never been there, but heard good things of of it. Guess I'll arrange a visit to see if DS likes it. Thanks a lot for the suggestion!