To be honest, my query about raising speed limits was somewhat speculative, and if there's much to be discussed on the matter it probably belongs in its own thread- which I'll start if there's likely to be much to be said on the matter.
I'm not familiar with the "nuts and bolts" of what would be required to (for example) raise the linespeed of the West Somerset to say 40mph (where geometry and structures would feasibly permit it), so I'm happy to be educated by those with expertise. If we want to increase public transport use and reduce congestion, perhaps the blanket 25mph ceiling of Light Railway Orders could be amended where conditions allow? Obviously any upgrades would need to be paid for, but maybe the DfT could introduce grants for this where such investment would have a positive effect on the local environment?
Though I am just "spit-balling" here, as our friends across the pond say!
What matters with speed, & affects the visit time / length of line decisions, is the average speed for a typical visitor trip.
If a typical visitor is willing to spend 1/2hr each way, having got off & looked around station B, then you can work out what might be an ideal line length.
Average 20mph gives a length of 10miles from A to B. If you only average 10mph, then it's a length of 5miles.
You'd also have to persuade NR to allow GWSR trains to use the existing tracks 2.7km south to Cheltenham Spa station (which only has two main line platforms), alongside the existing stabling siding on the east side of the tracks, which I believe is quite heavily used. That feels like a big ask given existing traffic volumes on that line.
A Cheltenham mainline connection for the GWSR won't happen;
far too much infrastructure works needed to get there (missing bridges, major embankments that haven't had much maintenance, removal of a cycle route)
busy mainline with no space for sidings/shunting
junction at Cheltenham Spa is south facing, so could only come in from the south
IF the GWSR go for a NR connection, there is only Honeybourne. It was designed as a major junction, with space for sidings.
It would be a long extension, but it's unlikely that the 2 intermediate halts would be worth rebuilding.
Unlikely to happen any time soon. It would cost a fortune for no real gain. Inly people who would benefit on race days would be the racegoers.
Those race day services are profitable.
The firm that promotes them also have coach transfers from Moreton to Toddington, & run the Northern Belle to Evesham with a coach transfer again (only Gold Cup day, which is 1 of 4 days for Cheltenham Festival)
There's more big days at Cheltenham, which might be doable if there was a direct transfer at Honeybourne.