2tph London Waterloo - Portsmouth Harbour
Calling at: Clapham Junction, Woking, Guildford, Godalming, Haslemere, Liphook, Liss, Petersfield, Rowlands Castle, Havant, Bedhampton, Hilsea, Fratton, Portsmouth & Southsea, PORTSMOUTH HARBOUR
So a slower service to/from Portsmouth? I'm sure that will please a lot of people! I can't see many of the smaller stations (Liphook, Liss, Rowlands Castle, Bedhampton & Hilsea) requiring 2tph to/from London, off peak and Godalming needing 4tph.
Two things to consider.
Firstly, this is likely post Crossrail 2 and so frequencies now may not be suitable in the future (for example a place may get 1,000 new homes built and so the increase in population justify more services).
Secondly, how many people would if wanting to head to Portsmouth at around 12:40 would wait until 13:30 for the train taking 1:30 (so arriving at 14:00) over getting the 13:00 and getting to Portsmouth at 14:43?
If that's not going to happen much, then it's likely that a consistent journey time wouldn't impact rail use, however could see a more balanced loading between the 2tph.
In the peak hours, maybe and it's worth having some faster services. However, off peak (and bearing in mind the cost to the passenger is the same, so it's not like the railway is able to charge more for the faster services) the impact on passenger numbers is likely to be limited.
One other factor, and it's not my suggestion so don't know, it could be that to keep the listing of services simple that the "service" is it could call at those stations (up to 2tph), however there is scope to skip stations if there was a reason to do so (for example to give a comparable fast journey time).