Gordon Brown issued a thinly veiled swipe at Tony Blair today as he hit out at politicians who fail to keep promises to step down from office after two terms.
The former prime minister grinned as he delivered the verdict during his first substantial Parliamentary appearance since quitting as Labour leader in May.
Mr Brown's fury at his predecessor's decision not to step down for him ahead of the 2005 general election has been documented in a number of high-profile Labour memoirs.
And today he appeared to seize an unexpected chance to make clear his own view during a two-hour evidence session to the international development select committee.
It came as Tory MP Pauline Latham challenged him over what action he had taken over African leaders who served more than the two terms they promised.
"People make it clear, as I have, to some of these leaders that if they say something and then are not in a position to deliver it then their authority is affected by that," he said.
"But I think it is very difficult for us to impose a rule on African countries that we do not apply ourselves," a smiling Mr Brown told the committee.
He did not refer directly to Mr Blair - citing instead the example of Michael Bloomberg who had proved an excellent mayor of New York despite serving beyond his self-imposed two-term limit.
But few observers were in any doubt to whom his comments were directed as he continued: "It is difficult for us to say, when sometimes in our countries people serve long terms, that there should be a limit on the terms. The real issue is keeping promises."
Mr Brown also hit back at criticism of his failure - apart from one short intervention in a late-night defence debate - to speak in the Commons chamber since losing power at the general election.
The ex-premier asked to give evidence to the committee - the same forum at which Mr Blair also first appeared after leaving Number 10 - rather than being invited.
Tory committee member Chris White questioned why he had delayed for so long and not chosen to speak out about international development in the House.
The former Labour leader hit out at the "unfortunate" diversion from the subject and insisted that "most former prime ministers have rarely spoken in the House at all".
He said he had decided to concentrate on his work as a constituency MP and international engagements but also took "a very big interest" in major political issues.
"I am here because I think I have a perspective on this that is of use to this committee. And I think it would be unfortunate if you were to suggest that there was only one way of making your views known in this House."
Mr Brown also expressed serious doubts about the coalition Government's prospect of meeting the United Nations goal of devoting 0.7% of GDP to overseas aid.
Spending plans show that figure being reached by the target date of 2013 but Mr Brown accused ministers of relying on a "one off" payment to the World Bank to get there.
He engaged in a hostile spat over the promise with Mrs Latham - which eventually required the intervention of committee chairman Malcolm Bruce.
It began when Mr Brown told the MPs: "As I understand it, the way to get to that target is a one-off payment to the World Bank and I don't think that will actually work.
"The most likely outcome, as I see it at the moment, is that we will not meet that target and there is an obligation on this committee ... to make sure this target is reached."
Mrs Latham reacted angrily to the former chancellor - insisting the Government was committed to reaching the target despite a difficult economic situation "which you are only too well aware of".
She pointed to rising payments to the World Bank under Labour and told Mr Brown he had no evidence to deny that sustained investment from the UK would continue beyond 2013.
"Let's see. I hope that's the case," he said - pointing out that less money was required to meet the target than if the UK economy was growing rapidly.
"It would have been nice if we had been left with that situation," she retorted.
In a two-hour plus session, Mr Brown also backed the idea of a global banking levy to help boost funding for Africa and avoid a "lost decade" in which the continent's potential was wasted.
He said private sector short-termism was to blame for a lack of investment in Africa and called on firms to show more imagination.
The former premier said he would soon publish a book, with other authors, on how the UN's Millennium Development Goals could still be met.