The second "stamp" allows them to track how long you were in the country and which country to left through (which may not check on exit either). For visas (especially EU) this is a big deal, because you (as a US citizen) are not required to apply for a short term business/tourist visa, but you can't stay more than 30days. If you exit through the UK, however, you may not receive the exit stamp (e.g. EuroStar). They may then deny you re-entry due to the apparent violation.
If you Eurostar out from schengen to the UK, you pass through schengen exit check, then a few yards later Uk entry check.
I assume that Americans get exit stamps at the first check.
Most countries that stamp passports give entry and exit stamps, whether you have a visa or not. More and more counties rely on computers to keep track of you though - Israel used to stamp you at Tel Aviv, now you get a piece of paper that you return on exit (you still et stamped at Erez when going in/out of Gaza). In 2015 Australia stamped when you use the manual system, but not the automatic system. I don't recall if the US stamped my passport last time on the way in, I don't think Canada did. Hong Kong stopped in 2013 I think.
It's a shame, I like stamps. Plenty of them at Lagos last month though - 2 stamps on the way in, 2 on the way out, as well as the full page visa.
I think the Eurostar is the only port of exit in the U.K. where I _have_ had my passport checked - at least at my airport, exit passport checks are only random
By airline/train or UKBF staff? There’s a difference as airport staff won’t check visa validity etc or do the entry checks that are the subject of this chain.
UKBF checks passports on departure at the Eurostar. At manchester airport at least, there are no routine outbound passport checks by UKBF
No, that's actually French border control. On the Eurostar, you clear the destination border when you check in, so that when you arrive you simply walk out.
I got into a bit of trouble once in a flight to Switzerland before it was in the shengen. I took the train into Italy, flew from Italy to Berlin, and on the flight back, the exit visa agents wanted to know why I didn’t have an entry stamp (they do random checks on the train, so no stamp).
