Locos Units and Coaches
These are model I think should be produced and why, some are single survivor
GWR
4-4-0 Let start with City of Truro - no explanation required, I'd buy one, suitable for GWR, BR and preserved lines.2-8-0T Quite a few preserved, and never an RTR model.
SR
02 0-4-4Very popular on the Isle of Wight, also there is a real one and no-one has ever done and RTR model.
LNER Moguls K1 2005 North York Moors and mainline, can do in apple green K4 3442 Servern Valley and mainline, can do in apple green
SDJR
7F Two preserved, I think they could be quite popularBR Class 14 Only one I can think of with no model current or shortlisted, with preserved examples Class 28 Could do with a current model - a very odd loco Electrics Could do with a early decent AC electric 81 or say 85
Multiple units GRCW 100 Quite common and never a model
123 & 124 Decent models of both of these Mark1 based DMUs could be popular, near 123 for Western Region, later on mix and match between both.Suburban DMUs From 115 to 118, 121, 122, 125, and 127 are all suburban DMUs. I think they could be done with 4 cab fronts (BR, Pressed Steel, BRCW, GRCW) three I think power car designs, and three trailers.
eg
116, 117, 118 same power cars with different fronts, 117, 118 same trailers, 115 & 116, 127 same trailers I think, 115 and 127 same power car bodies, not sure how similar to 116/7/8 they are. 125 DMBS is different to 116/7/8 AFAIR. However a good proportion of BR DMUs could be made from a limited amount of tools.Southern EMUs
4TC Ran with 33s, 73s, 430s can use some standard Mk1 bodies 4VEP Very commonCoaches GWR
Bachmann - produce a couple more Sunshines eg a Brake Third and Composite, not just the BCK and TK as featured on SVR and at Didcot Hawksworth stock - good looking, still some around, could get away with TK, BTK, CK Hornby - when you revamp your late 20s GWR stock please include the C54 TK the rest just need to be up to date.
LMS - models at last, can only think of period 1, and also the port hole stock
LNER Hornby extend your Gresleys GCR Barnum stock
SR lots of holes here LSWR IronClads 4 models I think will do the lot SECR non corridor stock, such as the birdcages
Off the wall ideas D84xx NBLs forgotten loco Baby Deltic Worth a punt GWR 47xx A big 2-8-0
4REP Very similar to 4TC change the chassis use your RBR and 1 new coach design gives you this, also need a good motor for your 12 coach train GWR Tourist stock Looks good and preserved GWR Churchward Toplights would look good SECR Corridor boat train stock - see KWVRSorry not up on modern units