I've been through the ticket barrier, luggage scan and customs at St. Pancras in 5 minutes. The longest it has ever taken me is 25 minutes. 10 - 15 minutes is typical. Brussels is usually quicker than London. Seats have more legroom than a Pendolino and you can choose where to sit. £90 return, £70 for Amsterdam. For me it is 1½ hours to Lille or 2 hours to Brussels. Add ½ hour and I've checked in to my hotel and on the way to a bar. So the problem with Eurostar is?