At a guess, cost comes into it. Once border control people are on board, they are whisked away to somewhere else and need to be brought home somehow. That may not coincide with a convenient reverse working (if indeed they have a requirement to work in both directions) and are not available to do 'actual work' for part of a shift.
Maybe?
Yes, and this is the real problem. One possible option is for UK entry controls to be carried out in Calais while the train waits, which is how it's done on many other borders. Schengen exit controls could be carried out at the same time, and it should be possible to create a system linking seat numbers to the passenger in advance. This way, anyone who needs further processing can be removed from the train in Calais, while the vast majority of passengers would need a quick scan of the passport and off they go.
by one posts that the France-UK border is so plagued with immigrants and so sensitive, comapared to Fin-Rus for example, that performing border checks on the train is simply impossible.
Which is hilarious, given that the Finnish border has serious problems with smuggling. For me, it's just an example of bad will, nothing more. If illegal immigrants are such an issue, then limit Eurostar on such journeys to UK+EU citizens and no more.
And/or (I suspect "or rather") Govt policy is not to let potential illegal immigrants across the border at all - which would mean border controls between Lille and Calais-Frethun perhaps?
It's what, 25 minutes or something between Lille and Calais? 25 minutes there, plus 15 minutes to remove anyone in Calais should be more than enough time to carry out border control.
The problem is that there's a huge charade about border controls in the first place. Most people are quickly checked with minimum fuss, even on 'hard' external borders like Poland-Belarus. I went to Belarus two years ago, and it took no more than 20 seconds to get through the police controls into Belarus, with another ten seconds while they looked in my bag for drugs.
