Jesus fucking wept, and well he might!
This country, contrary to a fair few others, has had a virtual open door policy ever since Empire Windrush! We are a small island with finite space and resources yet we wlcomed German Jews, Poles, Czechs, and refugees from virtually every conflict since.
Letting everyone in who we would like to swamps a limited jobs market, a limited space for homes, shops, factories, a Health Sevice that is being swamped more every day - France, a country that we have twice rescued from their own military ineptitude, which is of far greater size and a relatively less dense population than UK happilly shepherds refugees to Calais and turns a blind eye as they, the refugees, cross the Channel to UK.
Sooner or later, with or without further immigration, just via current birth rate, we are going to be living standing up for lack of space and eating Goddess knows what 'cos we have no more agricultural land.
Sooner or later, and probably sooner we are going to have to close our doors to protect all those here of whatever race and culture from the consequences of our habit of looking after ever underdog who comes, with or without justification, begging at our door to be let in!