KEZIA Dugdale’s flagship plan on the constitution has been dismissed as a “pretty ropey idea” by a former Labour minister, adding to the impression of a policy in disarray.

Brian Wilson said he shared people’s “confusion” about what a new People’s Constitutional Convention looking at federalism would achieve in practice.

He predicted the idea, the centrepiece of this weekend's Scottish Labour’s conference in Perth, would not work because there was no appetite for federalism - the combination of a UK-wide central government and strong regional governments - in England.

Read more: May urges voters to send message to SNP on second referendum

He cited the failure of Labour’s plan for regional devolution in 2004 under then deputy Labour PM John Prescott, when voters rejected a north east regional assembly four-to-one.

He said that without such regional devolution, a federal UK would be dominated by England, because of the lopsided, or “asymmetrical”, balance of power.

Labour delegates endorsed Ms Dugdale’s plan in the first item of business on Friday.

Addressing a Fabian Society fringe event the next day, Mr Wilson, a minister from 1997 to 2003, was asked how the convention would work in practice.

He said: “I’m not responsible for it. It sounds to me a pretty ropey idea, I have to say.

“I don’t have a problem with federalism, but the basic problem is that England doesn’t want federalism. This was John Prescott’s solution. The problem is the asymmetry of it.

Read more: May urges voters to send message to SNP on second referendum

“The only way you get symmetry is if the English regions had any interest in it, and they don’t.

“Well, they didn’t. I doubt if they do now. You’d spend a hell of a lot of time and effort finding out and probably get the same answer.

“I’m not sure what another constitutional convention would do except create another platform for the demands with which we’re all familiar.

“I would share your confusion on what a constitutional convention would do.”

Squeezed by the SNP and Tories, Ms Dugdale wants federalism to be her party’s distinctive third way on the constitution, with Holyrood getting vastly more powers inside the Union.

But interviewed on BBC Sunday Politics, she struggled to explain how the convention would deliver UK-wide federalism when there was no evidence people wanted it in England.

She also conceded it was not UK Labour party policy to carve England into devolved regions in order to arrive at a federal UK.

In his speech to the conference yesterday, UK Labour leader Jeremy Corbyn also failed to mention federalism when he referred to the convention.

Instead he said it would “ensure political and economic power is genuinely distributed from bosses to workers, from landlords to communities, from bankers to people”.

Mr Corbyn has previously baulked at saying the convention would lead to a “new Act of Union”, despite Ms Dugdale making it integral to Scottish Labour’s position.

Although a supporter of home rule for Scotland, Ms Dugdale’s deputy Alex Rowley also failed to mention federalism or the convention in his closing speech to conference, when huge curtains were used to hide hundreds of empty seats from view.

Read more: May urges voters to send message to SNP on second referendum

Instead he referred to challenging “the unacceptable status quo of power and wealth being concentrated within a few square miles of London” and the “centralisation of power and control away from our communities in Scotland and into Holyrood among a Scottish elite.”

Unlike Ms Dugdale, Mr Rowley voted for Mr Corbyn in last year’s leadership election.

Mr Wilson also suggested Mr Corbyn’s leadership was the biggest threat to the Union, as people may feel there was no alternative to Tory governments at Westminster.

He said: “To me the biggest danger on the constitutional front doesn’t come from people wanting independence, it comes from people’s frustration that eventually they think they’re never going to have another Labour government.

“If they think there’s going to be a Labour government, they won’t vote for independence. If they don’t think they’re going to have a Labour government, then it’s a lot more difficult.

“There is a direct relationship between the credibility of the Labour party in the United Kingdom and the ability to hold our constitutional line in Scotland.”

Scottish Conservative chief whip John Lamont said: “Brian Wilson's scepticism about Kezia Dugdale's Constitutional Convention is entirely justified and we can only share his confusion as to why his party wants to pursue it.

"Pro-UK parties need to face up to the SNP's plans for separation, not tinker with the Union all over again. Scottish Labour's disunity over this unwanted plan only reinforces the point that it simply cannot be trusted to defend the UK."?

An SNP spokesman said: “This is a devastating analysis from within Kezia Dugdale’s own party – her plans for federalism are simply delusional, as they don't carry the UK-wide support that would be essential to make them remotely credible or deliverable.''

A Scottish Labour spokesman said: "As Kezia Dugdale has said, federalism does not have to be symmetric across the nations and regions of the UK.

“Labour's plan for a People's Constitutional Convention calls for reform of where political and economic power lies across the whole of the UK, not just in Scotland.

“Both the independence referendum in 2014 and the Brexit vote last year showed that people want change within the UK. Only Labour is offering a positive solution to that.

"Labour will not support any second independence referendum. The SNP should rule out another independence referendum altogether."