A working stable you can see into through a glass partition, in a 17th-century building on Horse Guards. Eleven pounds, an hour, and the horses are right there. Westminster 6 min walk.
Visiting The Household Cavalry Museum
Area: Central London
Category: Museums, Historic Sites, family
Entry: from £11
Rain exposure: you will stay bone dry
How long to allow: 2-4 hours recommended to fully explore