Obione, I understand what you are saying. But how are you going to stop it.
Perhaps we could borrow Trump's idea of building a wall all around the UK. At the moment, it is our European partners who are stopping illegal immigrants coming over, and who allow the UK to have border control staff in France to do that too.
Our European partners know that the immigrants want to come to the UK- so once we are no longer partners- do you really think they will keep them there, at such inconvenience and cost to them- Now they have to do so, as it is part of the deal.
The UK coast lines are long and very close to France, Belgium and Holland, and not that far from Danemark. I mean, you can swim across the Channel. How would you stop them?
Reciprocal agreements, partnerships, like marriages and families- always mean a degree of loss of independence, call it Sovereignty- and you always have to weigh the pros and cons. We will still continue to elect our MPs and Prime Minister- and they will still negotiate on our behalf. Many countries do say that the UK has a strange form of democracy, due to the First past the Post system which totally ignores a vast % of the population, sometimes the numerical majority- that seems totally bizarre to other democratic countries- and so is an unelected Chamber with so much influence (the Lords)... but that is the British way, and no-one else can decide for the British that it should be changed.