The SNP would balance the UK budget by the end of the next Parliament and borrow "only to invest" after that.

Secondly, the party would "return the deficit to its pre-crash, long-term average and thirdly, to set debt on a downward path".

That is "a clear alternative to five more years of austerity", Nicola Sturgeon says.

Image source, Getty Images

With childcare in the spotlight today, what is each party proposing?

We've pulled it all together for you in one place.

Nicola Sturgeon tells supporters there is growing inequality in the UK.

"By 2021 there could be more than 5m children across the UK, a number equivalent to the entire population of Scotland, living in poverty in one of the richest countries in the world," she says.

"That is shameful."

The SNP leader says austerity is a product of "political dogma [and] ideology".

Nicola Sturgeon says the SNP manifesto "sets out a clear plan to end Tory cuts, protect Scottish jobs and strengthen Scotland's hand".

She describes Scotland as "a country that is welcoming and outward-looking".

She adds: "SNP MPs will work every day to make Scotland's voice heard."

And Scotland's first minister tells supporters the Conservatives' "true colours" are being exposed and the SNP need to "keep them in check".

She says that "Labour isn't strong enough to do that".

BBC Radio 4

Also on Woman's Hour, Jeremy Corbyn was asked about the issue of Scottish independence. He refused to say he would block another vote before Brexit is complete if Holyrood passed a motion on the timing, saying only he would "urge them very strongly" to delay it.

The Labour leader said he would allow a second referendum "if the Scottish Parliament and the Scottish people want it" because that is the "whole point" of devolution.

But he said he "would urge them to think again and I would appeal to the Scottish people to think again on this".

"Let's deal with the Brexit negotiations first, it's absolutely key that we get tariff-free trade access to the European market, our manufacturing industry relies on that, it's also important we have good agreements with Europe in the future in respect of management of the sea and all the other conditions that we've gained out of European membership."

"Welcome to the manifesto launch of the real opposition," says SNP deputy leader Angus Robertson.

He says SNP MPs at Westminster will provide a "strong, progressive voice" against "an unopposed, hardline Tory government".

The SNP's local candidate, Pete Wishart, is the one who opens proceedings at the launch.

"We have held the constituencies here since 1995," he says, "and we are not going to let this constituency go again."

He adds that Perth and North Perthshire is a Tory target seat but describes it as "a line in the sand that they will not cross".

Norman Smith
Assistant political editor

This was on a par, or possibly even worse, than Diane Abbott getting into a pickle on the cost of Labour's policing pledges.

Jeremy Corbyn was clearly struggling badly on the day's key policy and it raises all the sorts of questions that Labour has been dogged by.

Just how clear, how thorough, how diligent are its spending plans?

Here's the scene ahead of the SNP's manifesto launch in Perth.

It was originally due to be launched last Tuesday but was postponed because of the Manchester bomb attack.

SNP deputy leader Angus Robertson - who has led the party's MPs at Westminster - is expected to open proceedings.

He will be followed by leader Nicola Sturgeon.

Image source, PA

Ahead of that interview on Woman's Hour, Jeremy Corbyn visited a nursery to promote his childcare policy - a reminder, it would expand 30 hours of free provision to all two to four-year-olds.

He then, as we've been telling you, wasn't able to say how much it would cost.

Image source, PA

BBC Radio 4

Jeremy Corbyn was also asked whether he is still vice-president of the Campaign for Nuclear Disarmament because it says so on the group's website.

The Labour leader said he didn't think so and was surprised to learn that the website hasn't been updated.

His manifesto, of course, commits to renewal of the UK's nuclear weapons system Trident.

BBC Radio 4

On Woman's Hour, Jeremy Corbyn was asked how much it would cost to provide non means-tested child care for 1.3m children.

"It will obviously cost a lot to do so, we accept that," he said, adding that Labour wants to make childcare universal and will fund it mainly through corporation tax changes.

Asked whether he has the figures, he said: "Yes I do."

Pressed, he said: "I'll give you the figure in a moment."

"You're logging into your iPad here," presenter Emma Barnett observes.

"Can I give you the exact figure in a moment please?" the Labour leader said.

Asked whether this indicated that voters cannot trust Labour with their money, he answered: "Not at all."

He argued that investing in children in early years means they do better in school and added: "I want to give you an accurate figure."

Eventually, presenter Emma Barnett quotes shadow education secretary Angela Rayner, who was on Today earlier: "£2.7bn, then £4.8bn... with half a billion to reverse cuts to the Sure Start scheme. Does that sound about right?"

"It does sound correct," Mr Corbyn says.