What is ‘one in, one out’ migrant deal between UK and France?

The UK and France have reached an agreement to try to stem the flow of migrants making the crossing from France to the UK via the English Channel. The development comes against the backdrop of a visit from French President Emmanuel Macron to the United Kingdom for a summit with Keir Starmer. But what do we know about the ‘one in, one out’ deal? Will it stop the boats?

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