The Eurostar (read history here) exists since November 14, 1994 when our King and Queen inaugurated it. (THE QUEEN too of course)!
Two weeks later I also used it for the first time to visit my son in London. Of course everybody told me that I was crazy and it would be dangerous to go through a tunnel which was built under the sea and I should think of all the water and ships above me. I have to admit it was quite a strange idea travelling under water ! But it was a wonderful and smooth trip without any problems. Since then I have taken it many times.
You are only 20 min in this huge tube which is the tunnel and you don't see anything of course but the walls on each side and so close that if you could have opened the window and stretched out your arm you could have touched them.
This train allows up to 300 km/h (186 miles), but you don't feel anything only that the landscape runs by very fast and you can hardly see the cows (Belgium) and on the other side sheeps (UK).
Of course the train has become a big competitor to ferry boats and airplanes wich were needed to go to the UK. But now it's so easy, from Brussels to London it only takes about 2 1/2 h and you have to be at the station half an hour before departure and not 2 or 3h like for the airplane nowadays. For me it's even shorter to Ashford it will only be 1h 1/2. The train only stoppes in Lille (France) and in Ashford before arriving at its final destination London.
If I have time on sunday I can certainly tell more about my trip. Considering that I have to change train I never know (with my wonderful orientation sense) in which city I will finally arrive ! Maybe I can write you from Manchester or Glasgow ??