A senior Labour figure has condemned the party's "absolutely unforgivable" election failure and claimed Ed Miliband was surrounded by "pointy-heads" who did not know how to connect with voters.
Shadow transport secretary Michael Dugher also hit out at the leadership's widely-mocked decision to carve key pledges into a stone slab, calling it a "12-foot, granite, marble, cock-up".
He lashed out at the party's efforts in Scotland, claiming it had paid the price for an independence referendum campaign it had "fucked up" and blaming some Labour politicians for neglecting seats they had assumed to be safe north of the border.
In a strongly-worded attack on the team around Miliband, Dugher told the New Statesman the Labour leadership had ignored the threat Ukip posed in working class communities like his Barnsley East seat and the party had failed to connect with its traditional supporters.
"Working-class voters are not core vote any more - you saw that in Scotland, you saw that in England," he says. "When we fail politically, we fail the people that we came into politics to represent. I find that - being entirely self-critical - absolutely unforgivable."
He said Labour had to reach out to the "aspirational middle class" but also had to acknowledge that its message needed to reach working class voters too.
Dugher said: "I've always thought that politics is 90% emotion. All parties need a combination of people with different talents and reaches. Ed was very intellectual, he had a brilliant brain; he felt that ideas were the most important thing in politics. And he's right.
"But I sometimes felt that he surrounded himself with too many people who were socially just like him: all living within a stone's throw of each other in north London, all had been to the same university, and all kind of intellectual -academics."
Dugher, who said he had told Miliband about his concerns, added: "It was too many pointy-heads and too few street fighters.
"As a leader, you've got to surround yourself with different people. Ed had some of those people, so I don't want to overstate it. But too many were just like him. And, for them, politics was 90% intellectual. If the big thing out there is anti-politics, you've got to show that, actually, you do get it, you are in touch, and you understand.
"When I say it's 90% emotional, the new axis we've got in politics now - the politics of identity - is all about how people feel. We've got to get wise to that."
Labour was reduced to just one MP in Scotland as its former strongholds were overwhelmed by the SNP surge.
Dugher blamed the cross-party Better Together campaign in the independence referendum for the humiliation, claiming that Labour fell into a trap laid by the SNP.
"Scotland and our approach to it was an unmitigated disaster. We totally fucked up that referendum campaign - and that would almost be a generous and kind interpretation," he said.
"There was a highly visible elephant trap that the SNP set for us, which is that Labour and No would be for the status quo, for Westminster, for London, for the old political establishment and elites - and Scottish Labour all joined hands and they jumped into that elephant trap.
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"We shouldn't have been in bed with the Tories. It was a complete strategic disaster. It killed us. It should have been a contest between two competing alternative visions for a changed Scotland."
The dramatic reverse in Scotland was also partly down to the "politics of neglect", with "a number of people who had not delivered a leaflet in decades".
Miliband's stone carved with the party's six key election pledges, was widely mocked and dubbed the "Edstone", but Dugher said it was not to blame for the election defeat.
"Every campaign has balls-ups," he said. "That was a kind of 12-foot, granite, marble, cock-up. But did it change the weather? Nah."
With Labour set to elect a new leader, Dugher said the process should not be rushed.
"I don't think we should have a coronation. And it's perfectly possible for us to chew gum and walk at the same time. We can have a thorough internal debate about our way forward while going after this Tory government."