Michael Heseltine, as government cabinet minister, then over-ruled the British Rail recommended route, and laid down that it should go via Thames Gateway, terminating at St Pancras.
This added not only length but major tunnelling – through the North Downs, under the Thames, and much of the way through East and Central London in bored tunnel to St Pancras. Some quarter of the route is in tunnel.
In comparison I would expect that virtually all the French TGV route, which I do not know, is basically on the surface, in a far less densely populated country.
Thus the cost of the UK route, is far more per unit length than the French ones.
PHILIP SULLEY, THE GLASS HOUSE, BENOVER, YALDING, MAIDSTONE, KENT ME18 6AU