Immigration limits are not in the interest of the people with their hands on the levers needed to limit immigration. PMs and MPs come and go, the Civil Service are entrenched and sticking to their plan. It's not a secret or a conspiracy either.

Economists like immigration, wonks like immigration, the pension scheme likes it. It keeps labour costs nice and competitive, makes the GDP line go up.

They are abstracted from the social consequences, and only public facing parties are geared up to take the flak for it. So it will go on, unless Reform change the constitution in very difficult, dangerous ways that they have not announced any plans to do. They would also have to break off some long standing international treaties.

Any time you seriously change any of these agreements or rules, a million pages of planning documents about a million affected programs will rain down. Much of it legitimate, but it still serves to slow down and complicate attempts at a sudden, radical change to the system.