3 days in London - 6yo & 2yo - recommendations?

[car1sberg]

Would love some tips on places to go (and avoid) when we spend 3 days in London next week. We're staying very central, and are keen to do the usual touristy things so have a few of those planned.
Any must haves for children our ages? Is the rainforest cafe worth a trip? Anywhere else similar?
Thank you!

Include a ride on a big red London bus even if it is only a couple of stops- you can do a bus tour but these are expensive and it is fairly easy to use the normal London bus's (I used to be a tour guide on one of the tour bus's!)
Princess Diana memorial playground in Hyde park is fab (pirate ship,mermaid shell,indian camp etc...and free
Trip on the river (river taxi ) lots to see and a rest for your feet
Covent garden has lots of street performers also leister square
Science museum and natural history museum worth a visit (free)
St James park (they have pelicans) with picnic bought from fortums and masons near picadily (lovely cakes!)
Kings cross station for Harry Potter platform 9 and 3/4 if you are nearby and interested (has a trolley half in/out of the wall)
Harods has a good toy dept if you can't face the crowds at Hamleys

Rainforest cafe has a nice atmosphere - hard to say if its worth a trip

I would check out the tube walking map and only use tube when logical as often walking bus more interesting and easy

Hopefully some other people will have some good ideas for you