A former Labour Treasury minister has said admitted he has "burnt with the shame" of his infamous "there is no money" letter that hampered the party's election campaign.
Byrne said he had been ashamed of it every day since 2010 when he left the note for his Liberal Democrat successor David Laws.
It became a favourite prop of David Cameron, who regularly produced it on the campaign trail to show the severity of what the coalition inherited and imply Labour had a flippant attitude to it.
Cameron wields a copy of the letter on the campaign trail
Writing in the Observer, Byrne said: "Party members ask me: what on earth were you thinking? But members of the public ask: how could you do something so crass? And so bloody offensive?
"I've asked myself that question every day for five years and, believe me, every day I have burnt with the shame of it, nowhere more than when standing on doorsteps with good comrades, listening to voters demanding to know what I thought I was playing at. It was always excruciating."
In the one-line letter, Byrne told the then-chief secretary to the Treasury: "I'm afraid there is no money", and signed off wishing him "good luck!".
Byrne, who held his Hodge Hill seat in Birmingham with a massive 23,000 vote majority, acknowledged his actions had allowed the Conservatives to "bash" Labour's economic record.
He added: "People's anger - and my party's anger - at me will never ever match my anger with myself or my remorse at such a crass mistake. I made it easy for our opponents to bash our economic record by bashing me.
"And for millions of people and businesses who have had to make such sacrifices over the last five years, there was nothing funny about the national debt when the national task of cutting it has brought them such pain in their everyday life."
Byrne said he wrote the note after "tough and bruising" coalition negotiations which ended in failure for Labour and forced them from office.
He wrote: "I was writing thank-you notes to my incredible team of civil servants. And then I thought I’d write one letter more to my successor. Into my head came the phrase I’d used to negotiate all those massive savings with my colleagues: 'I’m afraid there is no money'.
"I knew my successor’s job was tough. I guess I wanted to offer them a friendly word on their first day in one of government’s hardest jobs by honouring an old tradition that stretched back to Churchill in the 1930s and the Tory chancellor Reginald Maudling, who bounced down the steps of the Treasury in 1964 to tell Jim Callaghan: “Sorry to leave it in such a mess, old cock.”
During the campaign, Ed Balls defended the letter saying it was "a joke".