Howard Credit:Kerrie Leishman How Howard was going to lead his party to victory when he could not hold his own seat is a question of great mystery. Now for the first time he "reveals" he intended to stand down as Liberal leader in December 2006 but was prevented from doing so - mainly by me, but also by his colleagues and then by Kevin Rudd and lastly by his own family. So if you want to know who caused all this catastrophe it is Peter Costello. John Howard was responsible for everything except his own retirement, which was all the fault of . . . well, you know the story by now. He couldn't go, he says, in July 2006 because I pushed him too hard; he would look as if he was running from me. He couldn't go in December 2006 because Kevin Rudd was elected Labor leader and he would look as if he was running from Rudd.

He couldn't go when his cabinet advised him to leave in September 2007 because, according to his family, it would look as if he was running from the voters. George Bush described him as a man of steel. He sent troops into combat. But he couldn't carry out his planned retirement because he might have received a few taunts from his enemies? He would have received a lot more plaudits from his real friends. Or perhaps he never did intend to stand down. There is not a skerrick of objective evidence to support his supposed retirement plan. He told no one. He tells us that if he had told anyone he might have become a lame duck because people might have thought he was going when he really wanted them to think he was staying. In years to come, it will be a Trivial Pursuit question to name the two prime ministers who lost their own seats. The other won his seat back.

So silly us for believing what he wanted us to think. Another reason that he told no one might have been because he wanted to keep all his options and didn't want anyone to hold him to a departure just in case the polls picked up and he could get another term. He had been flirting with plans to leave on and off over a long time. In 1994 he gave a solemn, witnessed undertaking he would only serve one term. In 2000 he speculated on radio that he would leave on his 64th birthday. Two months before the November poll in 2007, he asked the cabinet to tell him whether he should go. And it did. But he rejected that advice. He loved the job and all that came with it. He had done nothing except politics all his adult life, and at his age there was little prospect of another career. The honest truth is that when the time came he would never have been able to let go - not voluntarily. The only way he was going to leave was when the voters took him out, which the people of Bennelong did in 2007. It was a tragic miscalculation. In years to come, it will be a Trivial Pursuit question to name the two prime ministers who lost their own seats. The other won his seat back. It took another John - John Alexander - to win back Bennelong for the Liberals.

In any political career there are failures. You don't make them go away by denying them. An honest acknowledgement allows you to focus on the successes. I have written of Howard's many achievements in my book - there were four election victories for starters. But the worst thing about blaming others for your failures is that it invites people to re-evaluate a whole lot of other things as well. During the difficult period when I was attempting to implement the GST, a highly confidential memo written by the then-president of the Liberal Party, Shane Stone, mysteriously leaked out of the Howard office. Howard never managed to find out how it happened. The essence of Stone's complaint was that the government was seen as ''mean and tricky''. The charge was principally directed at me. But as the years wore on the description was more frequently levelled at Howard. On the night of the 1998 election, having survived by a whisker, Howard said he would commit himself ''very genuinely to the case of true reconciliation''. When there was a genuine spirit of goodwill about Aboriginal reconciliation in 2000 it would not have hurt to embrace it and walk across the Sydney Harbour Bridge. It didn't mean you agreed with every demand every person walking that day wanted to make. It would have shown a generosity of spirit. Now that he has retired, it would not take much to show some generosity about the achievements of colleagues who worked tirelessly over a decade for the government. A true leader can rejoice in the success of those around him. He does not need to demean their achievements and blame them for his own miscalculation.

And all these tricky gymnastics about whether he was or wasn't going to go. When is a promise not a promise? When is a deal not a deal? It was all just a distraction from what I belatedly realised: John Howard was never going to stand aside for anyone. He never had and he never would. This might have been the right thing, according to his family. But that was not the point. The point was whether he did the right thing by those MPs who would go on to lose their seats in the 2007 election. Some of them have never had a job since. And more, the point is whether he did the best thing for the Liberal Party and the best thing for the country? If you happen to believe, as I do, that we have had a bad government for the past three years, you realise how important it was for the Coalition, in 2007, to do everything it could to renew itself and extend its term in government. Loading The failure to do so was not in the interest of the nation or its people. I cannot take the credit for that. The principal credit for that failure must go to the person who was responsible. It belongs squarely to John Howard.

Peter Costello was federal treasurer from 1996 to 2007.