I have just remembered that I have a copy of Oakwood’s The Bognor Regis Branch Line (Jordan, 2009). I can find no references to the GWR operating normal services to Bognor, but it is clear that it was a popular destination for excursions, even if the council disliked the trippers disturbing the peace of longer stay visitors. Normally the trains seem to have been worked by SR locos, mostly LBSCR types, but a few LSWR and SECR types appeared.
I would guess that the trains were ‘one-off’ excursions, rather than regular holiday services; although these might repeat every year if popular. Bognor seems to have been one of the resorts that expected a reasonable amount of ‘select’ visitors who would arrive on regular trains, rather than large numbers of hoi-polloi.
Up to the change of the town’s name, it seems to have always been referred to as Bognor and the addition of Regis was probably not approved until 1930. It would be highly unlikely, very much a case of lésé-majesté, to call it Bognor Regis before the name was officially approved.
