The small Harry Beck Gallery was well hidden (and looked to be closed), but also worth the effort to find, chronicling in brief the development of the classic London Underground 'diagram' (apparently, to purists, it is not a map).
Compared to most museums and galleries here and abroad, it's very child-friendly (which is not, to my mind, necessarily a good thing, as there were lots of them milling around everywhere). Compared to most museums abroad, the gift shop is very well stocked. In fact, it's such a contrast to Germany and the Czech Republic, where they seemed almost ashamed to sell you tawdry souvenirs. The 'London Transport' brand is available in every shape and size, as well as the compulsory train-spotter books and DVDs. Some items seemed a little hard to justify - I rather doubt they sell many CD-ROMs of the Johnson typeface at £17 a time, and it's stretching the idea of London Transport to include the latest Harry Potter DVD in the museum shop. I was tempted by the 'Underground Maps of the World' book but in the end plumped only for 'Mr Beck's Underground Map', which tells the tale of Beck's revolutionary and unsurpassed design.