Little kids in London

My sister is visiting in feb with her 3 & 5 year old kids.  We want to go to London for a few days.  What are good things to do with kids that age in London?

http://www.viewlondon.co.uk/home_feat_where_kidsintow.asp
http://www.londonnet.co.uk/ln/out/ent/kids.html
http://www.kidslovelondon.com/

The Tate Modern is hands down the most kid friendly gallery to go to in London.  Little kids love the view and the massive hall, plus there is plenty of places to sit and take a break.  Right outside is a good run around place and the Millenium Bridge.

The Natural History Museum and the Science Museum are right together and are both favorites with little kids.  Lots of buttons to push and things to look at.  The dinosaur section is great.

The London Zoo is big on conservation and can even be done on a rainy day(the reptile and aquarium are worth a visit).  The shop is an excellent place to buy souvenirs.  And you can see where the snake scene from Harry Potter was shot.

If you like to clamber on and off buses and trains The London Transport Museum is worth a visit.  And again has a good gift shop for London souvenirs.

Excellent!  thanks.  Does anyone have any favourite things they do with kids in London?

Oh and make sure you check out the websites for special childrens' programs and events.  Both the Tate Modern and the Tate Britian have really good drawing activities that give you a focus to your trip.

It'll probably be a bit cold but you can't beat a boat ride along the Thames