If I understand the Brexiteers correctly, part of the concept is that the jobs in the UK that were previously filled by foreigners will now be largely filled by Britons.
It's more complex than that, I think.
Freedom of Movement in the EU has allowed employers to recruit from agencies across Europe. This has many benefits, including the ability to fill seasonal and temporary vacancies far more readily than we're now able to do.
However, it carries with it several disadvantages, too.
One is that it artificially depresses wages, because there are some jobs which the employer is almost always going to find it cheaper to use agency workers from low-wage economies to fill vacancies than it is to improve pay and conditions to fill them locally.
To a certain type of younger Thatcherite, that's artificially depressing the market, so now it's possible, we can improve wages and conditions by forcing the employer to improve them or go out of business.
Same goes for agriculture -- can't farm the land profitably unless we subsidise you, and even then you can't harvest the food or slaughter and butcher the livestock because you offer such bad pay and conditions? OK, wholesalers will have to look elsewhere, and pay more if necessary, and you'll have find something else to do with the land we are prepared to subsidise, often including rewilding it.
As background, this is a news item from 2017:
Markowski brothers given six-year prison terms after conning staff supplied by agency to Shirebrook warehouse
www.theguardian.com
Evernote link
I'm originally from Nottingham, so I know those areas, and the other traditionally Labour "Red Wall" constituencies in the north Midlands that were strongly pro-Brexit and voted Tory for the first time in 2019.
That's how they see the EU and Freedom of Movement -- not only does it allow a situation in which agencies like that can operate but that it also allows a situation in which the major, and often only, employer (in this case, Sports Direct, a very major and controversial retailer) is one where they can fill vacancies with slave labour, if necessary.
A generation ago, Margaret Thatcher devastated these old industrial areas, and some look as if they'll never make a full recovery while Sports Direct or Amazon can recruit temporary workers from low-wage EU counties.
People like Kwasi Kwarteng, the Business Secretary whose interview I keep mentioning, say well, in that case, turn off the supply of agency workers and we'll see what happens when they have to do more to attract staff locally, and keep them longer, and people like what they hear.
Let's see what happens. They did it a generation ago when they removed subsidies on failing industries in these areas, and denationalised, and ultimately closed the mines and many steelworks, and now they're doing it again by removing another distortion from the market.
ETA: I would far rather have fixed the problem by remaining in the EU and fixing it with UK legislation and enforcement of minimum employment standards and rates of pay, combined with encouraging trades union membership, but I'm a socialist, so obviously the Tories and I see things a bit differently. We've now left the EU and they're doing it their way. I hope it works.