@BluntFatball immigrants who come here to work do take some of the lower paid work (in care homes and similar) so it's unlikely that the few highly paid immigrants out weigh them. I'd say that, may be, why GDP has fallen? I'm taking your word for it that it has, I've not done any personal research into this.
on the whole, public debate is not helped by name calling (although I defend it being done in private, we all have to blow off steam occasionally). A reasoned discussion of what should be done to reduce this country's reliance on cheap foreign Labour needs to happen. Stopping immigration, without a plan, would be a disaster for our (already on their knees)care homes and NHS
I'd say, why not have a proper skill strategy that starts to plan for what skills we need for our future and then puts into action plans to realise that strategy (a Labour party promise) and also pay carers and the like £2:00 over the living wage (a Lib Dem promise)?
That way, we wouldn't be, as we are now, leaching workers, who may well be needed in their home countries, to come here to fill in the gaps out current population either cannot fill, because they don't have the required skills, or will not fill, because the salaries are too low.