Once upon a time, the outer suburban trains, by which I mean those that were all stations beyond Surbiton to Guildford via either Cobham or Woking, were fast from Surbiton to Waterloo and ran on the (now) fast lines. The Wimbledon stop was added in the late 1960s/early 1970s and eventually Clapham Junction too - I'd have to check the archive to determine exactly when. Subsequently they were moved the slow lines and Vauxhall and Earlsfield added too. As a result, what used to be regular use of those platforms stopped and they were fenced off to reduce risk, as has been done at several other places. Whilst there are additional trains calling at West Byfleet, Weybridge and Walton, and have been for some time, it does means the smaller stations that still only get the half-hourly stopper have seen an increased journey time. In the 1960s Esher - Waterloo was 24 mins with one stop; now it's 30 mins with five.