Tommyrot. First, of course no-one can precisely quantify the effects on the final result of the various issues that arose during the referendum campaign. But only a clown with his head in the sand would deny that immigration was either at the top or very close to the top of the list of crucial factors that swung the vote. All through the campaign we had talk of foreigners taking our jobs, driving down wages, of our taking back control of our borders, of immigration out of control, of the NHS overwhelmed, and then that Farage poster, not least. The vote was closer than 52-48 and you're trying to tell us that, without the immigration issue constantly to the fore, remain wouldn't have won handsomely?
If your appraisal of the 'Leave' vote is correct, what were the 'Remain' voters voting against?
If you are correct that "immigration was either at the top or very close to the top of the list of crucial factors" then can we assume that you, and those who voted with you, were already aware of this, and voting against Brexit on that basis?
If so, taking immigration out of the debate would have reduced voter turn-out on both sides.
In which case your idea of how this would have affected the outcome is groundless.