To be honest, this situation has been going on so long with this service I am amazed that no-one has come up with at least some sort of solution to mitigate it - that does not reflect well on GWR▸ .
What frustrates a lot of people is the perception that GWR are just happily sitting back, pocketing the extra revenue by the currently irresponsible operation of this service and doing nothing about it.
I'd be delighted to be corrected of course, if anyone "on the inside" can advise of GWRs plans to improve the situation specific to this service, that does not involve "manana, manana" because as we all know, the capacity increase provided by the new trains does not go anywhere near addressing the overcrowding if demand continues at its current rate.
It perhaps highlights the fact that there is no simple way of dealing with it given that pretty much all rolling stock is in use and virtually all of it very busy on other services. The 19:15 Swansea service has always been terribly full in the last few years and I wonder what impact the 19:12 Bristol service via Parkway has had on that? You could pinch the
HST▸ set that works the 17:50 Paddington to Worcester service and run that as a Turbo, but you'd need at least a 5-car to deal with passenger numbers and that results in two short formed suburban services (which are just as full). Perhaps come next May those units could be released by the extended new electric services?
Having done that though, you need to find a path to run an extra train (hence my suggestion of a 19:12 to Bristol splitting at Reading as it doesn't mean an extra path between Paddington and Reading), or possibly the 19:18 semi-fast to Oxford could be a 10-car
IET▸ from next summer with a portion for Oxford and a
B&H▸ portion to Westbury splitting at Reading? Both options will upset Newbury commuters though as they're slower and later than the 19:03.
The longer term solution will be to try and segregate the commuters from the longer distance travellers but until extra stock comes along I can't see any obvious options other than the few half-solutions that we've talked about, and would in all probability have a limited effect anyway.
Even then, free train paths are very scarce and as time goes on I become more convinced that serious consideration needs to be given to Heathrow Express being stopped in the peak hours (and perhaps all day) as that would be four more main line paths per hour straight into the back pocket now that constraints at Reading have been eased considerably.