//From all the surveys i have seen immigration into Britain was one of the leading concerns of Brexiteers.Perhaps i read the wrong papers.//
I think you will find, if you look deeper into the surveys (for what they're worth) the principle concern of people who wanted the UK to leave the EU as far as immigration was concerned is that 500 million people had the inalienable right to settle in the UK. No trouble with rubber boats or the back of lorries; they could simply pitch up at Heathrow or Gatwick, could not be refused permission to enter and could stay for so long as they liked. It was that uncontrolled legitimate migration that was the concern and which could be prevented, and which has now been stopped.
Many countries - both within the EU and elsewhere- suffer from illegal immigration and the UK is no different. Whether or not we belong to the EU will have no influence on that. The EU, for its part could help the situation for its members and the UK considerably if it ditched its ridiculous Schengen Agreement. But there's precious little chance of that.