Just for clarity here, in 2021 30,000 people came over in small boats and 10% of them were indeed illegal immigrants, so we're talking 3,000 people, which is not a significant portion of half a million.
(Of course, of the half a million people who moved to the UK, plenty of people left too, like I did a few years ago.)
But this is a discussion about boats and illegal immigrants, so the main figures are—3,000 illegal immigrants came over on boats last year. Presumably plenty of them were sent back too and had their rights to stay rejected, as is the law.
It's noticable that small boat crossings have shot up once 'Brexit' kicked in—from 299 in 2018, 1,843 in 2019, to 8,466 in 2020, roughly 30,000 in 2021. Brexiters seem to be endlessly incompetent, **** up the one thing they thought they were getting a handle on.