Yep Brexit stopped the UK returning migrants back to the EU. What you didn’t say was how many the uk had been returning, 289 in the year before Brexit. https://amp.theguardian.com/uk-news...fall-in-returns-of-boat-arrivals-since-brexit
If someone crosses on a boat and within a short time (IIRC 72 hours usually) goes to the authorities and claims asylum, the route of entry cannot be held against them and they cannot be prosecuted under international law. Far more illegal immigration involves walking through Heathrow with a valid visa and never leaving.
https://archive.is/COQ1n He would fit in with the guy in Sweden who's a refugee and against migrants.