Any illegal immigrant should not be allowed to remain in the country longer than 8 hours maximum. Remember, they are illegal immigrants and in effect, criminals. It is only the left wing corrupt lawyers and the wasters of civil servants in immigration and Border Force that are keeping them here.
Any seaman found in another country without permission - illegal immigrant, although classified as a displaced seaman, very rarely would they be allowed to roam the streets and sponge off the natives of that country. They would, as many know, be nicked and put behind bars with all due speed to get rid of them.
I worked in Sheerness Docks for a few years, whenever there was a ship berthed, naturally the crew wanted to stretch their legs and have a few beers and a meal ashore. There was never immigration far away from these crews, the Dock was crawling with them, all watching and listening.