Comment by tialaramex

Although the London Transport Museum is fun (some years back I decided to spend a week in my own capital city as a tourist, staying in a hotel in the centre, all day looking at stuff with tourists - and LTM is one of the things I decided to do) like most museums it does have a lot of stuff it can't display - but unlike most museums those things are sometimes huge like a bunch of buses, so they're not in a back room they're an entire other site, in Acton IIRC, the Depot, which is in fact open this weekend: https://www.ltmuseum.co.uk/whats-on/depot-open-days