Phil Spiegel said:
I used to suggest that the Channel Tunnel would have been built a long time ago (like when they first started it), if it was going to any other country

even if it was twice as long -which admittedly doesn"t give much choice.
Actually the French were quite cunning.
You may remember the Channel Tunnel was started at about the same time German Reunification was being talked about.
You may also be aware of the difficulties on D-Day caused by the weather in the channel.
So the Chunnel is there in case the Germans invade France again. It provides a quick route for us Brits to reinforce the French. And just in case they go into Belgium first, Eurostar goes there as well.