Clapham Common Station
Zone 2 Tube station on the Northern Line.
Along with Clapham North Station, it's one of only two stations on the Tube network that still use an underground in-tunnel island platform (a single platform serving two tracks, one on each side; not uncommon on the network — e.g. at Barons Court Station — but they're usually above-ground). This platform is quite narrow so can be a bit scary when crowded.