Ds (a lively 5.5 y.o.) and I have two days in London the week after Easter, just him and me (quality mum/son time!). He wants to go to the Zoo one day, we've already done the Natural History and Science Museums recently, and we can't do the London Eye or Aquarium because we've promised dh and dd not to go to these without them. Can anyone help me with any good ideas for what to do on our 2nd day in London?