Do we know the time frame for the Old Oak Common
GWML▸ platforms construction phase?
On your second point, Chris, I can see it now - the night riviera beneath the roof of the old
HS1▸ terminal at Waterloo. That aside, setting aside recollections of arriving on a
GWR▸ HST▸ at Marylebone, what percentage of Paddington's long distance services could be accommodated at another London terminus (and are the
IETs▸ compatible - do i recall an HST service ran to Waterloo for a while to provide connection to for trains to mainland Europe?).
On your third, while it's not a fast route: the value of through Bristol - Bath - Salisbury - Waterloo trains is the network connectivity provided by the likes of Clapham Junction and Waterloo, the value of easier travel between the intermediate towns it serves, comfort and flexible accommmodation giving accessibility benefits when travelling e.g. with children. Lastly, it's somewhat independent of the GWML so it improves the resilience of travel from London. If speed is also an issue, it's worth recalling that Bath to Waterloo via Salisbury originally took 2 hours 10 minutes before those trains were deaccellerated.
Mark
(Edited: typed 'HST ran to Paddington' when I meant 'HST ran to Waterloo')