Not 87-88. Northbounds left Poole fairly randomly (1M88 0625 MAN, 1S39 0834 GLC, 1E63 1038 NCL, 1M07 1238 MAN, 1M23 1458 LIV, 1M40 1732 LIV) with equivalent southbounds. The first two northbounds were from Paddington (1M09 0550 LPL, 1M10 0703 MAN) as were the last two southbounds, and so on.
OK thanks. Sounds not dissimilar to 1986-87: the Pooles (that I remember) left Reading around 0830 (Liverpool or Manchester), 1035 (Wessex Scot - Glasgow), 1235 (Newcastle) and 1640 (Liverpool). Reading was about 2 hours from Poole. Thus the 1987-88 timetable appears largely unchanged, except for the new 1238 Manchester service. This likely took the path of the Portsmouth-Manchester from Reading northwards, as this was 1434 from Reading in 1986.
So perhaps they did away with the Portsmouth services partly in order to provide an additional service from Poole, though I'm not sure what took the path of the former 0805 Portsmouth-Liverpool, around 0940 from Reading.
The 0550 Paddington in 1987 is also another long-standing 80s service, existing in 1982 (from Ealing Broadway) and 1983 onwards (from Paddington), calling Reading at 0630.
They don't have much beyond the 1982 GBTT for free though, whereas I can look at my personal collection for nothing...
For the "NSE" area they also have full timetables for 1981 and 1996; these also have summaries of IC services from key stations.
Further back they have a lot of Southern Region timetables from the first half of the 60s.