I'm pretty sure that platform 2 at Twickenham, a London-facing bay, is not used. Platform 1, also a London-facing bay, had its track removed a few years back after being derelict for ages; the platform is still there but lost in a jungle of weeds. Platform 2 was used back in the past for specials from Waterloo on rugby days at the stadium. The track at platform 2 was relaid a few years back, and the rebuilding of the station buildings allowed space for the platform to be turned from a bay into a through. However, a stout portable fence has been put up along the platform edge, the track is rusty, and I suspect that it's never actually been used since it was relaid.