As Hampstead is on the Jubilee line, we can get to it in under an hour from our patch of SE London. It seems a shame not to go, but I cannot visualise what my boys would find to do there, especially in the winter.
They will not enjoy walking on the heath for hours and hours. The oldest might like the book shops, but the youngest would be bored stiff. I do not want to spend shed loads of money up in this posh north london corner, entertaining and feeding them.
So can someone tell me if a cheapish, child friendly Hampstead exists or should I forget it?