Well David, there are nearly 2m people currently living in the UK who don't have a job, many of whom would be more than capable of picking your fruit which doesn't generally require the applicant to have impressive qualifications or a three digit IQ. They're unlikely to work for less than minimum wage because you're generously providing them with a caravan to sleep in though and I suspect that's what's causing the sleepless nights.
Why should we allow unlimited numbers of unskilled workers to come here to be exploited by rich landowners who then expect the taxpayer to foot the bill for topping up their wages through the benefits system? Mass immigration compresses wages, increases unemployment and puts an intolerable strain on schools, hospitals and services. It benefits nobody but the rich and powerful, much like the NFU which officially supports our continued membership of the EU.