(the Chertsey starter run as 73+hauled stock in 1979)
From September 1982 I used to see it passing through Surbiton -- unusual for a non-stop train to pass through platform 1 (the up slow). By then it was a single 4-VEP or 4-CIG (it's vaguely in my mind that it was often the latter, but I wouldn't put too much reliance on that).
My recollection is that the 50s replaced 33s on the Exeter trains in about 1980, and (I'm less certain of this, but it seems likely) that the MkIIs replaced MkIs at about the same time.
Given the Chertsey starter was a VEP or CIG by 1982 (and perhaps 1981 also?) could it therefore be that the 0716 from Southampton that I mentioned above might, by 1981, have been formed of the Mk-IIs which formed the (by then) 0910 Exeter? Hauled by a 73?
To continue: following up with the pattern in early SWT days (1997/98).
By then both the Portsmouth Direct and the SWML had 20-minute interval services, so you had xx00, xx20 and xx40 to Portsmouth and xx30, xx50, and xx10 to Southampton or beyond. The pattern out of Waterloo was (note all stopping patterns are from memory and might have minor inaccuracies):
xx00 Portsmouth fast (Woking, Guildford, Haslemere, Petersfield, Havant, Fratton, PSS, PH). Largely 442s.
xx03 Alton - fast to Woking then all. CIGs and VEPs.
xx09 Woking slow, must have used the slow lines throughout. I think this called Vauxhall, Clapham Junction, Wimbledon, Surbiton and all. 455s. By now Platform 3 at Woking was open so terminated there.
xx10 Southampton semi-fast. I think this was Farnborough-Basingstoke-Winchester-Eastleigh-Parkway. An unusual quirk with this service was that half the off-peak services were operated with 159s, not needed for the Exeter line off-peak. (There were 4 diagrams, 2 442, 2 159, with rather long turnarounds at Waterloo).
xx12 Basingstoke: Clapham, Surbiton, Woking and all. Largely VEPs, occasional CIG. Many services then formed the Basingstoke to Brighton via Fareham (headcode 31), which ran in the hours that there was no direct Reading-Brighton (anyone remember that?)
xx20 Portsmouth '82' - Clapham, Woking, Guildford, Farncombe, Godalming, Haslemere and all. CIG/BEP/CIG combinations, though buffet not open.
xx24 Haslemere slow: Clapham, Surbiton, Walton, Weybridge, Woking and all. Looped at Guildford to allow xx40 to pass (see below). 3 off-peak diagrams, 2 VEP, 1 CIG.
xx30 Weymouth express, fast to Winchester in these days. Largely unchanged from the 1967 pattern with the addition of Winchester, Parkway and Brockenhurst stops. 442s (single 442 off peak, double towards the peak; more double 442s on Saturdays)
xx33 Farnham: Surbiton, Woking and all. CIGs and VEPs.
xx35 Exeter (alternate hours) or Salisbury (alternate hours), I remember in the early days of 159s you had occasional quirky extensions beyond Salisbury to Tisbury or Gillingham in some hours, can't remember if these still applied then. Much the classic stopping pattern, with the Exeters running Basingstoke-Andover-Salisbury and the Salisburys all stations. Called at Clapham Junction by this time (introduced in 1989, I think)
xx40 Portsmouth express: I think this was ONLY Guildford, Havant, Fratton, PSS - I have a feeling this terminated at PSS, or at least some services did. Connected at Guildford with xx24 above to give three trains to Haslemere by changing. 442s, but single CIGs towards the peak - I seem to remember the 71 headcode for these.
xx39 Woking, as xx09 above
xx42 Portsmouth via Fareham. By this stage, for whatever reason, the semi-fast Portsmouth via Fareham, introduced in 1990, had been abandoned - but there was this slower service. Clapham, Surbiton, Woking then all. CIGs and VEPs. Interworked with Portsmouth-Southampton '85' stopper at Portsmouth, and some interworking with Farnham/Alton services at Waterloo. (Small chance I have got the xx12 and xx42 the wrong way round)
xx50 Poole semi-fast. Fairly sure this was largely unchanged from the classic xx45, stops were something like Clapham, Woking, Basingstoke, Winchester, Eastleigh, Parkway, Southampton Central, Totton (not classically called at), Brockenhurst, New Milton, Christchurch then all. 442s; single off-peak, double towards the peak; more doubles on Saturdays.
xx54 Guildford stopper, as per xx24 but terminating at Guildford. Two diagrams, both 4VEP.
The diagramming on the '97 timetable was something of a work of art: the aim appeared to be to use the 'best' available stock for off peak services to attract off-peak travel (if one assumes the 442 the most 'premium' stock, followed by CIGs, followed by VEPs). So all the Portsmouth fasts (xx00, xx40) were 442s off peak, and many Alton line services off-peak were CIG, rather than VEP. However as the evening peak approached, some of the 442s on the Portsmouth Direct were needed to double-up services heading to Bournemouth. So, some Portsmouth Directs (and xx10 Southampton services) were replaced by CIGs off Altons and Basingstoke stoppers, which were in turn replaced by VEPs from presumably Clapham Yard on the Alton and Basingstoke stoppers - which at that time of day were more suitable anyway for the slower services due to higher density.
Also I always thought the '97 timetable was a nice tradeoff between frequent services on a standardised pattern, and not overloading the railway. Not to mention interesting diagramming.