This EU referendum was always going to be a choice between the economy and immigration.
And so it proved today.
Iain Duncan Smith - fresh from his ministerial resignation - fired a missile in the direction of his old boss in Downing Street.
We should vote 'Leave', he told the audience at this speech - or risk being be poorer as a result of uncontrolled migration.
As members of the EU, IDS said, the UK would have to accept a population rise of 690,000 people over the next decade.
It was - he said - an increase the size of the city of Glasgow.
And to cope with that level of migration, the UK would have to build 240 new houses every day for the next 20 years.
All of which, he claimed, meant the EU helps the haves in our society, rather than the have-nots.
The have-nots, he said, suffer from increased house prices and they miss out on the growth in jobs - which are taken by those migrants from Europe who have lower overheads (they live in bedsits, they have no families to provide for, he claimed).
The result: a downward pressure on wages and an upward pressure on living costs.
He went on: the middle classes benefit from immigration in the form of cheap nannies from the Netherlands and cheap coffee shop staff from Croatia.
So far, so clear.
What, however, Mr Duncan Smith was not able to counter was the wealth of economic data which points towards an economic shock if the UK left the EU.
Because the Remain side claim an economic shock would be inevitable.
An economic shock that could lead to a loss of jobs.
A loss of jobs which could mean the have-nots lose out.
Will a car worker, they ask, in a plant in the North East of England become a 'have-not' if the demand for UK-made cars slumps after a UK exit from the EU?
I asked Mr Duncan Smith if he could be sure there wouldn't be an economic shock after a vote to Leave - he couldn't.
Instead, he said there was an also a valid economic risk to remaining in the EU.
I asked him, if current levels of migration were too high, what would be his preferred target?
He wouldn't give an answer but he did agree that net migration of 99,000 would be acceptable outside the EU.
I suspect for many - a 100,000 migration figure would still be a little too high (UKIP's Nigel Farage has argued for a figure less than half that) but it shows that even outside the EU, migration would still be difficult to control - especially if the UK economy continues to grow - as Leave campaigners like Mr Duncan Smith insist it will.