Video report by ITV News correspondent Rachel Younger
Jeremy Corbyn has faced an embarrassing gaffe when he found himself unable to provide the cost of his party's key manifesto plans on free child care during a radio interview.
The Labour leader was repeatedly asked on Radio 4's Woman's Hour to give a cost for his party's pledge to provide free child care to all two to four-year-olds, but after pausing several times he asked: "Can we come back to that in a moment?"
Mr Corybn was asked three times to confirm the key manifesto figure in the exchange filmed by Woman's Hour.
He was seen reaching for his iPad and being handed a copy of the manifesto by an assistant as he struggled for an answer.
Presenter Emma Barnett had opened the exchange by asking: "Let me understand then, how much will it cost to provide un-means tested childcare for 1.3 million children?"
Mr Corbyn replied: "It will cost ... it will obviously cost a lot to do so, we accept that."
Ms Barnett said: "I presume you have the figures?"
He replied: "Yes, I do. It does cost a lot to do it, the point I'm trying to make is that we're making it universal so that we are in a position to make sure that every child gets it and those that can, at the moment get free places will continue to get them, those that have to pay won't and we'll collect the money through taxation, mainly through corporate taxation."
Ms Barnett asked again, at which point Mr Corbyn said: "I'll give you the figure in a moment."
She went on: "You don't know it. You're logging into your iPad here. You've announced a major policy and you don't know how much it will cost."
Mr Corbyn replied: "Can I give you the exact figure in a moment?", adding: "All of our manifesto is fully costed and examined."
Ms Barnett continued: "You're holding your manifesto, you're flicking through it, you've got an iPad there, you've had a phone call while we're in here and you don't know how much it's going to cost."
Mr Corbyn then said: "Can we come back to that in a moment?"
The Labour leader, who had defended shadow home secretary Diane Abbott after a similar campaign interview gaffe, has put the creation of a "national education service" at the heart of his party's election campaign.
The plans would extend 30 hours of free childcare each week to all children before they start school.
Ms Barnett said it was "quite troubling" Mr Corbyn did not know the cost, adding, "It hardly inspires the voters."
The policy would benefit more than 1.3 million children as complex rules mean only 40% of two-year-olds qualify while many working parents with three and four-year-old children are missing out, according to Labour.
Ms Barnett later informed Mr Corbyn of the figure during the interview.
She said: "It's a staggering cost; would you like to know how much your policy is going to cost, Mr Corbyn?"
The Labour leader replied: "What is your estimate?"
Ms Barnett said: "It's actually Angela Rayner, your shadow education secretary. £2.7 billion and then £4.8 billion plus that with half a billion to reverse the cuts to the Sure Start scheme. Does that sound about right?"
Mr Corbyn responded: "It does sound correct, and the importance of restoring Sure Start is that this Conservative Government has actually cut a lot of Sure Start centres and closed a lot of them down and has damaged the chances of a lot of children."
Addressing claims that his office was run "chaotically", Mr Corbyn said: "Well, I beg your pardon, my office is not run chaotically at all. We have put together in two weeks - because the election was obviously unexpected - a comprehensive manifesto."
Ms Barnett has faced abuse online over her treatment of the Labour leader in the Woman's Hour interview, but speaking later at a Labour campaign event in Watford, Mr Corbyn robustly defended the presenter, saying no one should face abuse for "doing the job that they've been employed to do".
Mr Corbyn said that journalists were entitled to ask "difficult questions", and that those seeking elected office should expect to be "subject to permanent scrutiny".
Mr Corbyn also apologised for not being able to give the cost figure during his interview.
"I didn't have the exact figure in front of me so I was unable to answer that question for which, obviously, I apologise," he said.
"But I don't apologise for what's in the manifesto and I will explain exactly what the cost is.
"It's £4.8 billion it will cost by the end of the parliament and it means that one million children will get childcare - free childcare 30 hours per week between the years of two and four."