Is Conservative benefit freeze fair?
The prime minister often talks about benefits as if they are paid to people who don't work and paid for by people who do.
The truth is that the benefits freeze the chancellor announced yesterday will affect more than twice as many working families as workless families - seven million compared with three million.
The reason is simple - so many low income working families receive tax credits and, of course, everyone gets child benefit. What's more, this benefits freeze affects housing benefit when the previous 1% did not.
When I interviewed the prime minister this morning, I put it to him that he was hitting those he liked to call "hardworking families" at the same time as giving tax breaks to those who inherit pensions, buy a home or are millionaires.
Wouldn't a family with one partner working earning £25,000 a year think that it was unfair that they lost £500 a year when some people at this conference would spend that sum on dinner?
CAMERON: "I think it is fair to say benefits shouldn't be going up faster than the earnings of people who are paying the taxes to fund the benefits. I think this freeze to benefits is fair and it's accompanied by lifting the tax threshold so low paid people are helped".
ROBINSON: "As someone tries to afford the food bill or the gas bill, they're not looking at a graph of how benefits have gone up compared with earnings. What they're saying is we can't afford the school uniform. We can't afford the bill. And you're taking their money away?"
CAMERON: "We're going to cut their taxes. We've frozen for many households the council tax. We've cut petrol duty... When we can we are helping... We've also made sure the rich have paid their share... Fundamentally the worst thing for Britain's families is to ignore the deficit which is still too big, still adding to our debt, still a drag anchor on the economy... We've taken three million of the lowest paid people out of tax altogether. That's the choice we've made".
I also spoke to the prime minister about Europe. He rejected the warning of the President of the CBI, Mike Rake, that his promise of a referendum would damage future investment.
CAMERON: "Most businesses say to me 'at least when it comes to Europe you've got a strategy, a plan'....That's exactly what I've got".
ROBINSON: "What's plan B?"
CAMERON: "At the end of the day they'll be an in out referendum whether I'm successful or not... My view is I will succeed in this renegotiation".
I pointed out to the prime minister that his refusal to talk about a Plan B was precisely what he'd accused Alex Salmond of doing in the Scottish referendum. No Plan B emerged.
ROBINSON: "If the historians wrote you're the man who took Britain out of Europe would you feel proud or sad?
CAMERON: "I feel proud about what we've already achieved. We'll wait and see how this all goes... You've got to face up to big decisions. You've got to confront the big issues. We confronted the big issue over the future of the UK. We need to confront the big issue over the future of Britain in Europe. I have a plan and I'm going to deliver on that plan."
Earlier the Today programme's Jim Naughtie teased out a lovely admission from the PM when he asked him whether he'd be heartbroken if Britain left the EU - as he had said he would be about the break-up of the UK.
He said the integrity of the United Kingdom mattered "a thousand times more" to him than the country's relationship with the European Union.