The British Government past and present, have never asked the indigenous English if they are accepting of immigration into England? and so they should give the indigenous English in England a referendum on immigration into England.
With 3 main questions.

1 - Should there be mass unlimited immigration into England?

2 - should there be a controlled amount of immigration into England of 1, 2, 3, 4 or 5\%? with the past immigration into England being also reversed into a controlled amount of 1, 2, 3, 4 or 5\%?

3 - should there be no immigration into England and the past immigration reversed?