Living on the Chessington Branch it's almost entirely 455/456 combo's, regularly giving us 4, 6, 8 or 10 carriage combo's. Occasionally you see two 707's forming a 10 carriage train, but it's currently fairly rare. Not as rare however as the Sunday when a single 456 (2 carriage) appeared on one service, luckily it was a quiet service! I believe the 455 associated with the 456 failed at Waterloo, and the controller decided to continue with just the 456 rather than cancel the service.
In summer 2019 we got an evening 707 from Waterloo, which then ran ECS to Wimbledon Park Depot from Chessington South. So essentially a way to move a 707 into the depot! You could pretty much guarentee that you would hear passengers grumbling that the 'new' train being less comfortable than the 'normal trains'.