Ken Clarke has revealed he told Boris Johnson to "cool it" during last year's Conservative Party conference, as speculation that the mayor was positioning himself to replace David Cameron reached fever-pitch.
The Tory conference in Birmingham in 2012 was dominated by Boris, who was mobbed by the press on arrival at the city's station. He also held a "victory rally" in the conference centre to celebrate his re-election as mayor.
However Clarke said the "amazing mass media turnout" was a surprise even to Boris. "My advice was to him was I would cool it here, there isn't gong to be a vacancy for some years," he said.
Speaking to journalists in Westminster on Thursday afternoon, the cabinet minister without portfolio also said George Osborne was "bound to be a contender" to succeed Cameron once he stepped down as the chancellor was "playing a blinder" with the economy.
"My advice to George is the success of the economic policy will speak for itself," Clarke revealed. "George has the chance of coming out with a quite remarkable outcome".
Clarke said Osborne currently had the "biggest job in government" and there was a good chance that under his stewardship there was a chance he could say "under this term of office we've turned ourselves into a modern competitive economy".
Clarke, who has been an MP since 1970 and held almost all the major political offices of state including chancellor, health secretary and justice secretary, also revealed he may quit parliament at the next election.
The 73-year-old veteran Tory MP said he was currently at the point of "making up my mind" whether to seek reelection in 2015 and would make an announcement within the next two or three weeks.
He also said while he initially thought a hung parliament would be a "catastrophe", the Lib-Con coalition formed after 2010 was actually better than a minority Conservative government would have been. "We have delivered more than we could have as a single party government," he insisted.
Some Tory backbenchers, frustrated at what they see as a Lib Dem block on proper Tory policies have argued Cameron should have not entered a coalition. "What on Earth that was supposed to achieve I can't imagine," Clarke said. He said such a minority government would have "faffed around for six months" while "the world would have fallen around our ears".
Ken Clarke said David Cameron and President Obama made the right call on Syria
Having enthused about a wide range of foreign policy issues including the conflict in Syria, Britain's relationship with the United States and the European Union. Clarke was asked if he regretted never having been made foreign secretary. "The reason I was never foreign secretary was probably because I am so pro-European," he noted. "I'm not trying to get the set."
Clarke, one of the most pro-European Union MPs in the Conservative Party, repeated his criticism of eurosceptic Tories who want to use Cameron's promised 2017 in-or-out referendum to lead Britain out of the EU.
He said part of his current job was to help negotiate the planned EU-US free trade agreement and that outside the union the London's bargaining power with Washington would be "comically slight" compared to what it is within the bloc.
Clarke also warned that "isolationism is spreading through sensible members of the public" and that voters needed to be reminded that they could not shut themselves off from the world. He said the current combination of economic crisis and turmoil in the Middle East should "terrify us all".
Clarke was permitted to miss the crunch vote on whether to use military action against Syria as he was unable to get back from a family holiday. However he said he fully supported the prime minister's decision to advocate force.
He said the vote could have been won if there had been more time to convince sceptical MPs of the value of punishing Bashar al-Assad for using chemical weapons. The quick vote, he said, "showed the prime minister's anxiety to get parliamentary approval before we found ourselves doing things with the Americans".
"The timing was not of our choosing," he added. "Within another week we could have got a majority".