Jabird
But a train needs a nose at each end - so that would be completely un-even, and also, demand would be the other way round. Also, calling at this island would add - I guess a good 25 minutes to the time of any train using the HS1 line. Totally different to skirting round Lyon and Paris, where the mileage might be a bit more, but you are cutting out a very slow trundle through the city.
The TGVs do have a nose at each end. They run two trains joined together, nose to nose. Then when it gets to Lyons or perhaps CDG, they split the train into two smaller ones. Simples.
And I do not see this adding much time to the Paris-London journey. Supposing the Isle of Grain site for a minute, the track only needs deviating by, say 10km. Train pulls into Silver-Boris, train is split while the passengers alight and board, and off it goes again - one half to the north of England and the other half to London.
Extra 5 mins at most. And you can always have an express that does not stop at Silver-Boris.
Jabird
La gare est un éléphant blanc
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Well done, we've gone down from 2km to 300m now
Apples and Oranges.
The 2km is between Euston and Kings Cross, the 300m is between St Pancras and Kings Cross. Effectively, the latter pair are the same station, with a road running between them.
The 2km between Euston and Kings Cross is important, because this is the gap between HS1 and HS2. You have still not addressed this problem at all -- it is completely unacceptable to have a high speed rail network, with a thumping great 2km gap in the middle of it. It is madness in the extreme, and nobody will say why this is being contemplated.
P.S. Lyon is not a white elephant, it is a white dinosaur. And while it is rather empty at times, the trains that run through it are not. Almost full every time I go on it, and not just with businessmen either - every man and his dog uses the TGV.
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