Jeremy Corbyn struggled to remember the cost of Labour's pledge to provide 30 hours of free childcare a week for children aged between 2 and 4 years old in a live interview on BBC Radio 4.
The Labour leader said his party's policy was to replace the existing "patchwork of preschool opportunities" with a universal offer of 30 hours free childcare a week, paid for by the government, regardless of a family's background.
Fresh from a relatively successful interview with Jeremy Paxman, the Labour leader struggled to cost the policy in a discussion with the BBC's Emma Barnett.
How much will Labour's childcare plans cost? Leader @jeremycorbyn couldn't answer on @BBCRadio4 #womanshour… https://t.co/tFwHZFVvg2
This is the exchange on how much the policy cost:
Emma Barnett: How much will it cost to provide un-means-tested childcare for 1.3 million children?
Jeremy Corbyn: Um, it will cost, it will obviously cost a lot to do so, we accept that.
EB: I presume you have the figures?
JC: Yes I do. It does cost a lot to do it. The point I'm trying to make is 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.
EB: So how much will it cost?
JC: I'll give you the figure in a moment.
EB: You don't know it? You're logging into your iPad here. You've launched a major policy and you don't know much it'll cost.
JC: Can I give you the exact figure in a moment, please?
EB: Is this not exactly the issue with people and the Labour party which came up under Gordon Brown, that we cannot trust you with our money?
JC: Not at all.
EB: You don't know the figure.
JC: All of our manifesto is fully costed and examined.
EB: You're holding your manifesto, 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?
JC: Can we come back to that in a moment?
EB: What when you've looked it up. My point is it's quite troubling, it's a policy you're launching today, Mr Corbyn, and you don't know how much it's going to cost. It hardly inspires the voters.
JC: I think what is important for the voters to understand is that if we don't invest in our children and we don't invest in them for the future then they do less well in primary school, less well in secondary school, and less well in the future.
EB: But you don't know the cost.
JC: I want to give you an accurate figure.
EB: Why on earth are you giving free childcare to people can afford it? If it's un-means-tested, you don't have the figure, hopefully someone's emailing it to you.
JC: The important thing is that all children get a chance to grow up together. At the moment we have a system which separates out in the sense that a child of wealthy parents may well be able to go to a paid-for preschool or nursery facility. Others will not get that chance because their parents can't afford it or if they're poor will get a free space.
EB: This is a very expensive policy, My Corbyn, I'm going to help you out with the figures. I've got them. Would you like to hear how much it's going to cost?
JC: What we think is it's more important to invest for the whole community and collect the money back through taxation on the principle of universalism. The same applies with the National Health Service and applies with mainstream education.
EB: It's a staggering cost, would you like to know how much your policy is going to cost, Mr Corbyn?
JC: What is your estimate?
EB: 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 cuts to the Sure Start scheme.
JC: It does sound correct.
Corbyn also struggled on the issue of his role with the Campaign for Nuclear Disarmament, telling Barnett, "I don't think I am the vice president of the CND." The organisation's website lists him as one of 10 vice presidents.