This country is cr*p at forward planning, then foreigners often get the blame. Lack of British dentists for years, decreasing number willing to do NHS work etc, so the UK entices dentists to come from abroad. Then folk moan 'can't even see a British dentist, they're all foreign!' Decreasing number of GPs, many taking early retirement, not enough British people enticed by that route into medical care. So the UK entices GPs to come from abroad. Then folk moan 'can't even see a British GP, they're all foreign!' The crisis in these sectors has been known about for YEARS, very little gets done and then as usual it's '11th hour panic' mode ... throw £££ at people to come from abroad ... and then moan cause 'we have too many foreigners.'
Because this country is cr*p at forward planning and has a race to the bottom (pay wise) in a lot of sectors, we'd be lost without foreign labour. Oh, and good luck if you think British workers will be eager to pick up the slack e.g. by going to pick and sort veg for 12 hour shifts on minimum wage or clean toilets. Yeah, good luck with that.
p.s. for clarity, I have absolutely no issue with this country welcoming people from other countries to work and settle here.