Ken Follett, the millionaire thriller writer, has lavished £100,000 of his fortune on the apparently doomed campaign by Ed Balls to become Labour leader.
The six-figure donation will give fresh impetus to the shadow Education Secretary's attempt to succeed his political mentor Gordon Brown.
Despite putting up a spirited fight, Mr Balls seems to be lagging behind David and Ed Miliband in the battle for the Labour crown.
But Mr Follett last month pumped another £100,000 into his campaign, the Electoral Commission disclosed as it published the major donations – gifts of more than £1,500 – to the Labour hopefuls in July.
The author is no doubt a fervent admirer of Mr Balls's leadership credentials, but conspiracy theorists might detect an after-shock from the Blair years. Mr Balls was firmly in the anti-Blair camp in the in-fighting that beset Labour in government.
Mr Follett, a long-standing Labour supporter whose wife Barbara was an MP for 13 years until she stood down at the general election, had a spectacular fall-out with Mr Blair soon after he became leader.
He described the former prime minister as "immoral, unmanly and lacking conviction" and claimed he would be remembered for making "malicious gossip an everyday tool of modern British government".
Mr Follett was not available last night to explain the reasons for his gift, while a spokesman for Mr Balls declined to comment.
Almost half of the £310,000 pledged last month to the leadership contenders was paid into David Miliband's coffers.
He received almost £139,000, including £50,000 from Anthony Bailey, a Labour fundraiser who gave money to both Mr Blair and Mr Brown, and nearly £33,000 from the former minister Lord Sainsbury.
Sir Gulam Noon, the "curry king" businessman, handed over £10,000 to the shadow Foreign Secretary's campaign, while the film producer Duncan Kenworthy donated £5,000.
Mr Miliband said: "It's humbling that people are giving up both their time and their money to help me."
Ed Miliband lagged behind his older brother, collecting £46,450 for his campaign, well over half of which (£28,000) came from the GMB union.
A spokesman said he had also received close to £60,000 from hundreds of backers whose donations were too small to notify to the Electoral Commission.
Perhaps the most surprising donation was the £10,000 given by Jamie Carragher, the Liverpool defender, to Andy Burnham, a supporter of the club's arch-rivals Everton.
The shadow Health Secretary, who received donations of £12,400 and a £10,000 loan, said the figures did not take into account the "fivers and tenners" being contributed through his campaign website.
For the second month, the fifth leadership contender, Diane Abbott, did not receive any donations of more than £1,500.
In the contest to become the party's candidate for London Mayor, Ken Livingstone raised £35,000, including £10,000 from the union Unite and £5,000 from the train drivers' union Aslef.
His rival, the former MP Oona King, collected £14,000, including £10,000 from the media mogul Lord Alli and £2,000 from the television historian Simon Schama.
Labour leadership donors
David Miliband £138,835.12
Including: £50,000 from Anthony Bailey; £32,835.12 from Lord Sainsbury; £25,000 from the Usdaw union; and £10,000 from Gulam Noon.
Ed Miliband £46,500
Including: £28,000 from the GMB union; £5,000 from Betterworld Ltd; and £5,000 from Q Hotels Group Ltd.
Ed Balls £103,000
Including: £100,000 from Ken Follett, pictured top with his wife, Barbara, the former Labour MP for Stevenage.
Andy Burnham £22,400
Including: £10,000 from Jamie Carragher, a £10,000 loan from Kevin Lee
Diane Abbott £0