One-in, one-out

And shake it all about, say the politicians

The treaty between the United Kingdom and France on the prevention of dangerous journeys — a “one-in, one-out” pilot scheme as the government has called it — is certainly unusual. But that does not justify some of the confusion that seems to surround it.

A text was published on Tuesday and it came into force yesterday. I found the English-language version easy enough to follow, although far from complete. This is what I understand it to mean.