Lewisday - yes you've cracked it, so expanding a bit on thefab444's reply...
The pre-December 2007 SWT weekday 'Brighton' service was 'much less than hourly', for want of a better expression...
Looking at the services there were big gaps in the SWT service to make room for FGW's odd Brighton extensions, amongst other reasons.
For example the basic down pattern around 2005/6 was an xx24 off Basingstoke towards Brighton, of which roughly one service in three started back from Reading, and was a DMU - the other 2 of 3 would be 450s. They went through Fareham at about xx08 generally, but the first SWT arrival in Brighton all the way from Reading was the 0656 arriving at 0923. An earlier arrival was run by FGW, but from Portsmouth Harbour - it still runs.
The 1424 off Basingstoke terminated at Fareham, at 1507, with the onward path being taken up by an FGW service, and the current service from Great Malvern is basically its successor, however the standard timings on the West Coastway were altered slightly for SN's altered timetable for their new franchise, so the exact paths are now different.
However there were no early evening SWT arrivals at Brighton between 1815 and 2113 because the relevant departures from Basingstoke ran to Portsmouth instead - and they still do...
In the up direction SWT had a similar 'short' service starting at Fareham at 1005 - this was because FGW's early westbound service had taken the 0857 slot off Brighton. (And oddly enough, like the similar down service already mentioned it didn't form a connection with FGW at Fareham...)
SWT's longer distance services from Brighton beyond Salisbury to the west country were hardly what you'd call a frequent service, with only one train to Paignton on a Saturday and to Exeter on a Sunday, but in broad terms the paths were shared with FGW and the much reduced weekend SWT Basingstoke/Reading services - the Sat Paignton service left Brighton in the 0957 slot for instance...
