Biggest and Smallest
Two stations vie with each other as the biggest on the network, each with 10 platforms - Baker Street and Moorgate. Baker Street can be argued as the true holder of the title however as all are used by London Underground trains (4 Metropolitan, 2 Circle, 2 Bakerloo and 2 Jubilee) whereas four of Moorgate's are operated by NetworkRail operators (Thameslink 2 and WAGN 2) - the others are 2 Northern and 4 Circle and Metropolitan.
Similarly three stations compete for the title of the smallest station on the network, all having just one platform. Heathrow Terminal 4 station is unique in being the only tube station with a single platform edge, but the title is probably truly jointly owned by Chesham, one of the Northern outposts of the Metropolitan and Mill Hill East on the Northern. (Single line platforms were also in use on the Ongar branch of the Central and at Aldwych, both of which are now closed.)