In my post above, I tried to separate fantasy from reality. The major commercial centres on the
GW▸ main line are far too close together to allow much above 155 mph running. OK, a new
LGV▸ line with it's first stop at Bristol may just sneak into consideration, but would operators really forego the revenue on offer at Reading and Swindon and would such a line be cost effective? I would say doubtful, but would be interested to see a cogent financial argument. The original railway builders were visionaries, but also speculators and although some of their routes are still carrying traffic today, many more bit the dust well before Queen Victoria. Even in the 'Golden Age', financial considerations were to the fore.
With regard to services west of Exeter, heart would say wires to Plymouth and 125 mph running into Penzance. Head says 100-110 mph to Plymouth and doubling/resignalling to give a more robust and effective 90-100mph service in Cornwall.
I am aware of developments in the South West and of the economic woes in some areas of Cornwall, (which have far more complex root causes than just journey times to London/Bristol
BTW▸ ). As the son of a Cornishman and graduate of the UoP, my heart lies very much in that area. Although I would love to see an LGV running to Plymouth and even beyond, I just don't think it is economically feasible. Plymouth cannot be counted as anywhere near one of the
UK▸ 's most prosperous cities; as a look at the databases available at
http://www.socd.communities.gov.uk/socd/Welcome.aspx will show. It could be argued that improved communications could improve Plymouth's potential for growth, but not nearly enough to justify the gargantuan investment required to improve significantly, (i.e. more than a cut of 30 minutes to London), on current journey times west of Exeter.