They come on planes - fully paid but have destroyed passports. Lots come from the UK who have already failed asylum there - yet pretend to be from somewhere else. I believe (off the top of my head) that we also have 1500 per year allocated by the EU.
The common factor of nearly all of them is that they are undocumented and, frankly, mostly lying. Amongst the liars are some genuine ones but it's a small percentage. People aren't fooled anymore after meeting them/ dealing with them.

Ah, the benefits of self-identification…

'Brexit caused small boats crisis in English Channel', report finds.

Boris Johnson’s Brexit deal is the primary factor in the crisis of small boat crossings in the English Channel, a new study has found.

The decision to leave the EU without a returns agreement in place has led to the “skyrocketing” number of dangerous crossings, according to the Durham University report.

There you go, HOL brexit faithful.

'Brexit means brexit'.

So a young man from Syria arrives in France and decides that as the UK has left the EU he should not stay there but catch a boat to blighty? Eh

The reason the boat numbers has gone up is that our European allies are waiving them through and pointing out where to catch a dingy.

'Brexit caused small boats crisis in English Channel', report finds.

Boris Johnson’s Brexit deal is the primary factor in the crisis of small boat crossings in the English Channel, a new study has found.

The decision to leave the EU without a returns agreement in place has led to the “skyrocketing” number of dangerous crossings, according to the Durham University report.

There you go, HOL brexit faithful.

'Brexit means brexit'.

“When you choose an action, you choose the consequences of that action. When you desire a consequence you had damned well better take the action that would create it.” “We all make choices, but in the end our choices make us.” “We are free to choose our paths, but we can't choose the consequences that come with them.”

Brexit in a nutshell.