I guess service levels, quality of rolling stock, run down stations plus Travellers Fayre Station buffets were at the worst in the early 1980’s!
Not sure about 1980, as it was before I started using trains... but (as mentioned on another thread) the 1985 timetable on the South Western and South Central divisions of the Southern was a deterioration compared to a couple of years earlier. And the worst period under BR on the Waterloo lines from the POV of frequency, certainly, was around 1991-93. And as for the current era, don't want to get into that, but let's say there are both advantages and disadvantages compared to the 1980s...
That said, the period from about 1987-90 showed significant improvements in train frequency and electrification schemes, so that period, at least, was a 'good' one overall.
Back on topic though... the Guildford-Ascot line stations (Camberley being the prime example) had a direct off-peak service to Waterloo from around 1988-91 but haven't had one for many years since. I remember seeing an old 1972 timetable once and in that year, those stations had what can only be described as a superb service compared to what has prevailed since... two trains an hour (one splitting from a Reading train, one standalone) and limited-stop between Staines and Waterloo so presumably pretty fast overall. The pattern was xx00 Reading/Guildford (all stations Staines to Ascot), xx30 Guildford only (all stations beyond Staines) and xx40 Reading express (possibly fast Staines to Ascot, not 100% sure on that, then all stations). By 1982, though, the through trains had been lost except in the peaks. There were also some counter-peak through trains in the timetable at that time, but they were announced as only going to Ascot at Guildford, presumably to avoid people mistakenly going the (very) long way round to London.
In the same sort of area, ISTR Chertsey had a 'direct', principal stops only between Waterloo and Twickenham, then all stations (as opposed to all stations via Hounslow, so one could say that unlike now it had a 'usable' direct service) in the 1972 timetable, formed by detaching a portion off the Windsor service at Staines.