London culture for adult and 11 year old

[Eggsbaconsausage]

I've got 24 hours in London next weekend with my 11 year old. We would like to see a couple of museums/exhibitions and a show. They have quite mature tastes so we don't need something targetted at kids.
The last time we came to London we both enjoyed Grayson Perry at the Wallace Collection so something along those lines would be good.

If anyone could recommend specific exhibitions or shows or other experiences i'd be really grateful.

The banksy exhibition in South Kensington was well received when I went recently

Kerry James Marshall at the Royal Academy is incredible.

My Neighbour Totoro as I believe Studio Ghibli is ageless.

These are all excellent suggestions, keep them coming as I'm going to put together a list and let the kid choose

The London Transport Museum could be a fun interlude.They also do "Hidden London" tours including underground. Another thing -if fashion is of interest!- is to go to the permanent fashion exhibits at the V&A. Went with an 11-year old who was fascinated by the 18th century outfits on show.

There are various “treasure hunt” type activities in London that could be fun - you get clues to follow to go to various places and have to take a photo to prove you’ve been.

National Portrait Gallery
The Foundling Museum

Starlight Express

Any more shows for my shortlist?

Moco Galley near Marble Arch has is good and has various deals at the moment if you shop around on something like Travel Zoo
Operation Mincemeat for a show