Tom Anderson wrote:

The prices are actually pretty reasonable - a car plus a driver, who
spends the night in a seat in standard class, costs 103 UKP for a return;
it's 137 UKP if the driver wants a bunk. Given that a super advance return
just for a foot passenger is 54.00, that's really fairly cheap. I'm
thinking my next holiday might be down in Cornwall; now all i need is a
car ...

autoroute gives 612 miles return Paddington to Penzance.

Total cost by car at 40p per mile would be £245.
Fuel cost by car, at 12p per mile, would be £74.

And you'd have to spend 12 hours driving, and accept the associated
dangers of driving.

So £103 seems a bargain, if you live in London.

This service would need a stop on the M25 to be really useful. Another
case for Iver Parkway.