A great shame I only sold last week a book I've had since the 1990s entitled 'London Country in the 1970s' as surplus to my requirements. It had some nice photos, as well as text, but I'd not looked at it for donkey's years. I'm sure it would have provided some of the answers to questions posed here.
However, a book I do still have is entitled 'Country Buses Volume Three 1960-1969' by Laurie Akehurst, the definitive history of London Transport's Country Area in 3 volumes. The photo on the front cover is of a 401 bound for Upper Belvedere, but unfortunately there is no covering description of where and when the photo was taken. In the book though, in sections covering the mid 60s, are photos of RTs (a) standing at the Eardley Arms terminus of the 401 with blind showing Sevenoaks, so through journeys were offered; (b) on the 491 at the Woolwich Road stop just before the Upper Belvedere terminus, with blind already reset for Wilmington and (c) on the newly-extended 423 at Wrotham Square in 1964, going to Longfield Station the rather long way round! The caption of the 491 photo is informative: it says that most 491s turned into 467s when they got to Wilmington, and then went on to Sidcup Station. This helps explain why I often saw 467s with 491 canopy blinds etc. Also, from what I remember when I worked in the same office at LT with Mr Akehurst for a short time, he then lived in Belvedere, so I guess his info is gospel!