I was talking about this with a mate from work the other night and we couldn’t quite figure it out.
A few years ago when I was still in school a guy in my year decided to take all his savings and bought a one way ticket to Amsterdam with one of his friends. They spent all their money on drugs and then couldn’t afford to get back and were stuck over there for a while. I don’t know how they eventually got back but that’s another story.
Anyway, suppose they managed to hitchhike to Calais (with their passports) and then climbed into the back of a lorry to get back over here… what would immigration do if they caught them? Let them in? Send them back? Confine them to a life of buggery in jail?