> decently-sized Eurostar terminal

I think not having a "decently-sized terminal" is a much better approach. If I remember correctly (haven't taken a train across a non-Schengen border for a long time now, but https://travel.stackexchange.com/a/18563 seems to confirm), customs handling often happened on the train - the officers board the train at the last stop of country 1, do their passport checking etc. while the train was going to the first stop of country 2, and get off there.

Any move towards anything that would require a "terminal" as opposed to a platform will (on in the case of the Eurostar, was) just be the first step in making train travel as uncomfortable as air travel is today.

The Eurostar web site already mentions that you should be checking in 30 minutes in advance. I remember seeing the security checkpoint in London, shaking my head, and hoping this would not spread to other train lines.

The Channel Tunnel is covered by the Sangatte Protocol (1991) and the Additional Protocol to the Sangatte Protocol (2000), which together enforce pre-boarding immigration controls. (For comparison, the Treaty of Le Touquet introduced them for cross-Channel ferries in 2003.)

Ultimately British politics has driven all of this: it's much easier, legally, to refuse someone without documentation at the UK border control in France (or Belgium, or in the future Holland) than it is when they claim asylum upon arrival in the UK.

Customs do happen like that routinely on intra-Schengen trains. But intra-Schengen, there's no immigration to clear. In Eurostar terminals at Paris Nord, London St Pancras, Lille Europe and Brussels Zuid there are immigration checkpoints. The ones on the continent are manned by UK border agents, the one in London, by the French border patrol. This way, Eurostar trains are effectively intra-Schengen. Since you clear immigration at a checkpoint, they don't usually have roving customs officers on the trains.

The border checks are the main reason for the delay in extending the Eurostar to Amsterdam. There's going to be a border check on the platform: 15b. That's the same platform currently used for the Thalys to Paris, which doesn't require a border check.

At St. Pancras, it's not just security. You're clearing EU immigration as well. They don't do anything on the train and once you hit the EU, it's just as if you got off an intra-EU train.

In Amsterdam Central Station they are now building stuff for passport control, security checks, etc. This is on the east side, around platform 13 or something. I don't think it is all the way at the back (15) but I never bothered to find out. Certainly not a separate terminal.

Another interesting detail. I'm told that the Eurostar uses a train signalling system that is incompatible with the one used on the Dutch railways. Which basically means that they have to lock out the entire section between Amsterdam CS and the start of the HSL just to let one Eurostar go through.

I read on the Guardian that only the most recent Eurostar train model will be used for compatibility reasons.

My understanding is that it's going to be platform 15b, the east side of the platform closest to the IJ.

In my experience, at least if one books tickets only several days in advance, the train is not much more expensive, but often comparably. It might be different if you book several weeks in advance, though.

For example I just looked up the fares for a weekend trip Brussel - London on the coming weekend. Leaving after work on Friday, getting back Sunday evening.

  Eurostar: Brussel to London: 17:56 19:03
            London to Brussel: 19:34 22:38
            233€

  Cheapast Flight (Brussels Airlines): 16:55 17:05
                                       17:50 20:00
                                       196€

If it's in the same ballpark, I definitely prefer the train. Much more comfortable than a plane.

> The Paris and London Eurostar terminals are nice.

You have a very expansive definition of "nice".

St. Pancras station in London is quite nice. Gare du Nord station in Paris--not so much.

Gare du Nord gets, at best, the appellation of "workaday"--it's functional, mostly, but would not really appear on anybody's list of somewhere "nice".

St Pancras is "quite nice"?!

It's a wonderful building, both inside and out. I think it's one of the most beautiful buildings in Europe. Neo-gothic and wrought iron.

Image search: https://www.google.co.uk/search?q=st+pancras+international&t...

There could be more seating but it's pretty spectacular otherwise.

St Pancras is a beautiful piece of architecture, and has some nice shops, but the pattern of circulation was completely wrecked during the redevelopment, perhaps to encourage people to visit said shops. Happily, the one trip that isn't a massive pain is getting to and from the Eurostar terminal. Security is pretty quick to get through, but there's nothing much on the far side, so leave it until the last minute, and enjoy the station, or even better, if riskier,

Gare du Nord is architecturally pretty average for Paris, ie beautiful, at least from the outside. The shopping is disappointing: the best bakery for a last-thing-you-eat-in-France snack is a Paul, of which there are dozens in London anyway. Security is again pretty quick, and past it there are some comfortable enough chairs, and some overpriced and fairly useless shops.

The atmosphere inside St Pancras is better than inside Gare do Nord - it's brighter and arier. That's pretty much the only difference, though.

The Gare du Nord Eurostar terminal has been revamped in the last few years - it's much better than it used to be.

That's kind of scary, actually, given that my impression of Gare du Nord comes from only a couple months ago.

It looks a lot better from the outside than it actually is on the inside.

Lille's isn't so bad except for the fact that Lille-Europe pretty much only has Eurostar and Lille-Flandres is most everything else. It's walkable but a bit announcing.

Most TGVs that don't go through Paris depart from Lille-Europe rather than Lille-Flandre though. Lille-Flandre is mostly for local (non-TGV) traffic and Lille-Paris as far as I know.

There's also a metro connection between the two (one station) that is accessible for the disabled (... or people with heavy luggage) and that is free if you have a valid train ticket although it's not advertised anywhere.