I think bookworm is right; the Plod has the right to turn over any plane landing in the UK and request details of anybody on it.
However, that seems a pretty obvious statement of the hugely self evident!!!
If Plod didn't have this right, he may as well give up.
I suppose it is a rather strange thing to do to a wholly international flight landing in the UK for just a refuel for example, but again it's pretty obvious that these powers must exist.