The ghost of Labour past sends a shiver through corridors of No 10

The next time Charles Clarke and Ed Balls sit next to each other at a Norwich City football match, the conversation may be a little frosty, even though they will be cheering the same team.

Yesterday, Mr Balls led the counter-attacks against Mr Clarke after he called on Gordon Brown to stand down if he cannot turn around his fortunes soon.

"I think it's Charles being Charles," said Mr Balls, the Prime Minister's closest political ally. It is true that the former Home Secretary has "form" as Mr Brown's most vociferous critic.

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The two men are both political bruisers and have never been soulmates. Mr Clarke declared that it would have been better for Mr Brown to have opposed Tony Blair for the Labour leadership in 1994 rather than to have stood aside for him. "Gordon would have been humiliated in the election in 1994," Mr Clarke said. "But that has coloured their relationship for years. It is a complete delusion in Gordon's mind that if he had only run, he could have won."

The two men clashed bitterly inside the Blair Cabinet – over national identity cards, which Mr Brown fought against tooth and nail before changing his mind later, and university top-up fees, which Mr Clarke introduced as Education Secretary.

Two years ago, he said Mr Brown had "psychological" issues that he must confront, accusing him of being a "control freak" and "totally uncollegiate".

Mr Clarke was one of only seven Labour MPs who did not nominate Mr Brown to take over from Mr Blair last year. But some of the doubts he raised about the Prime Minister now ring true. "Can a leopard change its spots,?" he asked in 2006. "He's not a risk-taker and that matters, you've got to be a risk-taker in politics. The courage question is a big thing for Gordon." Others asked the same question after Mr Brown backed away from a general election last autumn.

What was the motive for his latest attack? Inevitably, Brown allies accused Mr Clarke of inflicting maximum damage and securing maximum publicity. That, they said, was why he had timed his intervention to coincide with Mr Brown's much-trumpeted autumn fightback.

That may damage Mr Clarke in the short term, since it is at odds with the Cabinet's decision to give Mr Brown "one more chance" to turn round his prospects over the next month or so, which will see him make a crucial speech at the Labour Party conference.

Mr Clarke has told friends he believed it was his duty to raise the issue of Mr Brown's leadership; that the party could not possibly have got through its annual conference in Manchester later this month without a debate erupting about it. He believes that, with Labour 20 points behind the Tories in the opinion polls, it was unrealistic for Mr Brown's supporters to hope the Prime Minister would enjoy a "unity conference".

Fellow critics said Mr Clarke had "done the party a favour" by putting the leadership issue on the agenda – and that his doubts about Mr Brown were widely shared among Labour MPs, even though none backed him up publicly yesterday.

"The Brown camp can't accuse Charles of sabotaging the relaunch. It had hardly been a great triumph before he intervened," said one, referring to Alistair Darling's doom-laden comments about the economy and a housing package overshadowed by a warning that Britain was about to enter a recession. Mr Clarke is something of a lone wolf, and admitted yesterday that he would almost certainly fail to muster enough support among Labour MPs to be a candidate in any leadership election.

Although seen as reckless by some colleagues, even his detractors admit that Mr Clarke has the courage he accuses Mr Brown of lacking. It is not a great surprise that he is the first MP to put his head above the parapet. Mr Brown's allies took some comfort from the fact that he had "shot his bolt", saying he would not attract so many headlines the next time. "Whenever Charles erupts, there's always a big fuss but then there's no follow up," said one Brown supporter.

Such confidence may prove to be misplaced this time.