As a regular Swanwick passenger it is immensely frustrating that due to the sheer journey time between Victoria and Swanwick direct it’s better, even if more expensive, to go to Southampton and change.
As an aside before I continue, I think more trains are needed on the Fareham - Southampton corridor; sadly due to the poor signalling down there it can’t happen. Towns such as Netley and Woolston are getting a lot bigger (as is St Denys) and they need a much better service.
On the South Coast, if I remember correctly you’ve got 5tph between Barnham and Havant with a Littlehampton - Southsea stopper, Victoria - Portsmouth, Victoria - Southampton, Brighton - Portsmouth and a Brighton - Southampton.
The biggest issue seems to have always been balancing the needs of the towns between Hove and Havant to give them a direct service to London (even if hourly) as well as services to Brighton and a spread of destinations like Portsmouth and Southampton. I believe the Littlehampton starter is done because they need the extra service via Chichester but don’t have capacity via Worthing?
Interestingly it’s also worth remembering under Connex the hourly service to Southampton at one point was a disasterous service from Littlehampton only which meant empty trains; and at other points it was a direct service to Bournemouth! How times change.
Personally, I’d like to see the operator keep the two fast Victoria - Havant via Horsham services (with portions); but ensure these two services are relatively fast along the Coastway west of Chichester. If that means one train stops at Emsworth and Havant and the other is Havant only then so be it; the passenger usage figures along the Coastway are pretty light at the small stations.
I’d also go so far as to operate both services from London to Southampton. The reason for this is that there are options for passengers on South West for cheaper tickets on slower trains and, with Portsmouth having 4tph via various routes to Waterloo, a token London service is of little use.
For these London to Southampton services, I’d call for both services to stop at Cosham, Fareham, Swanwick and St Denys (best connections to the Airport outside of Central), and have calls on one of two of the half-hourly services at Bedhampton, Portchester, Netley and Woolston.
For Coastway passengers between Barnham and Havant (local stations), I’d suggest the Brighton to Portsmouth services be ‘tucked in’ behind the Victoria to Southampton services at Ford so as to ensure good connections at Barnham; but also to further offer connections from Brighton to Bognor. The Brighton to Portsmouth services with various levels of stops on the Coast (west of Barnham, they’d be semi-fast from Hove to Barnham due to the West Worthing stoppers), would then go through to Portsmouth Harbour.
The Littlehampton additional service could be operated to Portsmouth & Southsea, Portsmouth Harbour, or it could even go to Winchester via Botley and then reverse via the Baltic Siding. With a stop at Hedge End (improves service there), and then at Eastleigh (good connections for local Coastway stations to Airport) it would actually be very useful.
With a need for a 5th train per hour between Fareham and Southampton, I’d look to decelerate the GWR slightly with an additional call at Swanwick (this used to happen in peak and is very useful for the numbers of leisure travellers I see in the area that use Swanwick as a railhead for other local towns), and I’d suggest splitting the Romsey Rounder so as the provide a service from Salisbury to Portsmouth (Dean, Dunbridge, Romsey, Southampton, St Denys, appropriate smaller stations, Swanwick, Fareham, Portchester, Cosham, Hilsea, Fratton, Portsmouth & Southsea) to relieve the Portsmouth - Cardiff and also to improve the service on the Three Rivers. The other service would be a Salisbury - Totton (Romsey, Chandlers Ford, Eastleigh, Airport, Swaythling, St Denys, Southampton, Millbrook, Redbridge, Totton). The Salisbury - Totton could be extended back to Swindon every 2 hours (improved service to Melksham etc) and to Yeovil Junction/Pen Mill every 2 hours (additional capacity west of Salisbury and new journey opportunities).