So, I get emails from Heathrow Connect and in my current email was a link to Quirky London Museums - maybe you've been to London multiple times and want something different to do...
I think I could be very fascinated by the Museum of Brands and may actually look that one up next time we travel to London. Also included in the list are Benjamin Franklin House, Ragged School Museum, Magic Circle Museum and the Grant Museum (mounted animals and animal skeletons including some rare/extinct animals), looks both fascinating and creepy - like something a preteen/teenage boy would enjoy!