Skilled immigration or the Channel crossing?
Unfortunately due to the Boris Wave, we got mass, unskilled legal migration.
The channel crossings are a rounding error compared to that (but should be stopped as well).
20 years ago it was mostly Poles whose only quality was that they were willing to work for less than native UK citizens in jobs that said UK citizens supposedly did not want to do (which is doublespeak for businesses not wanting to pay a decent wage). This kind of immigration was one of the reasons Brexit happened.
It was more the later additions to the EU a few years later that were actually problematic and got people's backs up.
It didn't help that we were allowed to restrict immigration from those countries but didn't as the government needed mass immigration to disguise the fact there was no growth.