I think that most people agree that unlimited immigration is not sustainable, but it was the language that Theresa May was using. Immigrants are taking our jobs, immigrants are forcing wages down, they are a strain on our services.
I found the following comments from Tom Bradby (ITV political commentator) quite interesting---------

He wrote, on his Facebook page.......


Sometimes, politicians do things that are really hard to understand.

Theresa May has just given a rather tough speech to the Tory Conference. In it, she said of immigration that the 'net economic and fiscal effect is close to zero.'

But here are a few obvious problems with that.

1) It was her government that promised more than five years ago to reduce immigration to the 'tens of thousands' so her speech can be read as an attack on her own policy and record in government.

2) We have no control over our borders because citizens of EU member states can come here at will. So far as I am aware, the government has no plans to attempt to change this.

3) The OBR (the independent statistical body set up by the government itself) issued a detailed study a few years ago on the long term impact of immigration on the public finances. It came up with some stark conclusions; if net immigration runs at a level of 140,000 per year for the next fifty years, our debt to GDP ratio would be 99%. But cut immigration to zero, it concluded, and you'd end up with a ratio of 174%. In other words, in a country with an ageing population as we are, a reasonable level of immigration is essential to keeping the public finances healthy. This is because most immigrants are educated elsewhere (which saves us a lot of money) and quite often return to their countries of origin in retirement (saving us a fortune in health and social care).

Of course, it is possible Theresa May doesn't actually read her government's own statistics but someone in her office surely must. And it is certainly hard to see how they fit with her claims today.