How do some politicians manage to resurrect their careers from the ashes of defeat or disgrace?Paul Evans says its all down to timing.Peter Mandelson's unexpected return to the frontline of British politics sent a frisson of excitement through Westminster. For some, it was evidence that a determined and talented politician can persevere through trial and scandal. For others, bringing back such a controversial figure to the cabinet was a sign of desperate government.

Mandelson epitomises the politician with unfinished business, refusing ever to accept that their career has been irretrievably derailed. What distinguishes his multiple returns from those of less successful politicians seems to be a particularly intense fierceness of character and cold determination to prove himself.

Mandelson appears to regard his career as a never-ending war with enemies - seen and unseen. On the night of his re-election as MP for Hartlepool in 2005 he made a defiant and angry victory speech, bellowing: "Before this campaign started it was said I was facing political oblivion - my career in tatters never to be part of the political living again. Well, they underestimated me because I am a fighter - and a fighter not a quitter."

That he had simply retained a safe Labour seat was irrelevant. For him, it marked the failure of his enemies to strip him of his destiny.

Lord Mandelson now takes his place on the red benches opposite Michael Heseltine, a figure once similarly driven to continue building his career regardless of obstacles. Having overcome a brush with near-bankruptcy, and characterisation as an unsteady maverick (most notably after wielding the Commons mace at gloating Labour MPs) he rose to the post of Defence Secretary.

After resigning in deep conflict with Margaret Thatcher over the Westland affair, he dug in as a backbench critic of the Prime Minister. It would have been easy for him to fade from prominence; to focus instead on his successful publishing business.

Instead he played an instrumental role in Thatcher's downfall, eventually becoming John Major's Deputy Prime Minister. Had it not been for a heart attack, he might have led the party after 1997.

Like Mandelson, Heseltine appeared to have a clear sense of narrative about his own career. Whether true or not, the oft-quoted claim that he mapped out his future political career while at Oxford illustrates the persona he created; that of an endlessly motivated man for whom no setback could lessen his ambition.

Politicians like Mandelson and Heseltine seem to drive on relentlessly as though the troubles they encounter are simply irritating distractions from their inevitable ascent.

Yet other politicians who have suffered setbacks reflect on their image, even on their principles, and conclude that - to be resuscitated in the eyes of the public - change is needed.

Following the loss of his Enfield seat in 1997, Michael Portillo returned to parliament in a byelection, seemingly having undergone a Damascene conversion from gung-ho rightist to born-again liberal. As Shadow Chancellor he immediately endorsed two totemic Labour policies: the minimum wage and Bank of England independence - and in 2001 ran for his party's leadership on a distinctly progressive platform.

Neither the parliamentary party or the grassroots was sufficiently convinced, while the wider public was left puzzled.

Eight years on from Portillo's famous defeat, Stephen Twigg, the man who beat him, faced the same loss of both his seat and ministerial job. While some of his similarly dethroned colleagues have accepted the end of their parliamentary careers, Twigg is determined to be back in parliament. In September last year he emerged from a wide field of candidates to replace deselected incumbent Bob Wareing as candidate for the traditionally solid Labour seat of Liverpool West Derby.

"It is a strange mix of emotions," he says, recalling the immediate aftermath of his defeat. "It does feel like a rejection, even if you can rationalise the issues. It felt personal, and it took quite a long time for that to pass."

In the months that followed, Twigg spent time with friends who had also lost their seats: Lorna Fitzimons and Oona King. "Talking to them made me sure that I wanted to be back in Parliament. Neither of them wanted to return immediately, but I felt very differently. When we shared experiences and regrets, they highlighted some of the things they didn't miss, whereas I was only remembering the things that I did miss."

By ignoring Michael Portillo's advice (he texted Twigg to suggest that he seek a byelection nomination) he has given himself time to get acquainted with the needs of a new constituency, and is passionate about tackling its underperforming schools.

Unlike Twigg, Liberal Democrat Sue Doughty is campaigning to recover Guildford - the seat she lost at the last general election. Acknowledging that her narrow defeat was "distressing", she believes that a successful comeback is dependent on maintaining a strong team of supporters.

"The team were keen to stress that we'd lost battle but not the war," she says. "Bloodied but unbowed, you have to rebuild self-belief in everyone around you.

"Fairly soon after the election I decided I wanted to stand again. The party was sure the seat was winnable and that I was the best one to win it. There were no recriminations."While for some, losing a parliamentary seat can be crushing to the fragile political ego, political history recounts numerous successful returns to Parliament by MPs dumped by their first constituencies.

Recovering a reputation hit by scandal can be a tough and long ordeal. Cecil Parkinson's ascending Parliamentary career came to a halt in 1983 when he resigned as Secretary of State for Trade and Industry following the revelation that his secretary, Sara Keays was pregnant with his child. Parkinson was beginning to rehabilitate himself at the Energy and Transport departments when Margaret Thatcher's resignation effectively ended his ministerial employment.

In 1997, after becoming Lord Parkinson of Carnforth, he made a surprise reappearance in frontline politics when he became the Conservative Party Chairman by William Hague. He retired in 1998 after feeling he would no longer be known as the ‘disgraced' Cecil Parkinson.

But for other politicians who have encountered disgrace or humiliation, attempts at returning to the fray can too easily descend into farce. In 1975 the Labour MP John Stonehouse was at the centre of one of the most bizarre episodes in British politics. Having faked his own death at sea in Australia to avoid facing financial woes (the tabloids initially asserted with confidence that he had been eaten by sharks), his deception was uncovered and he was extradited to face trial.

Despite encountering jeering crowds in his Walsall North constituency (a constituent noted at the time: "It's not guts he's got coming back here, it's just plain cheek") he actually returned to the Commons - eventually leaving the minority Labour government to sit as an English National MP in the months prior to his trial.

He insisted he was not finished politically right up until his imprisonment. The impossibility of having any future involvement in mainstream politics had apparently never quite sunk in.

More recently, then Secretary of State for Wales Ron Davies was forced from his job following a "moment of madness" involving a sexual liaison on Clapham Common. At the 2001 election, he stood down as an MP, but retained his seat in the Welsh Assembly. Later allegations that he had again been seen cruising for sex forced him to stand down as Labour candidate for his assembly seat - prompting him to plough a new political furrow with the small Forward Wales Party.

In 2007 he again bid unsuccessfully to return to the Welsh Assembly, this time as an independent. What motivates politicians like Davies to compound their abasement when there is no realistic hope of resurrecting their careers?

Lucy Beresford is a psychotherapist who recently prompted raised eyebrows with her description of Gordon Brown as "deeply insecure" on the BBC's Daily Politics. She believes that the answer liesin the personality types typically drawn to politics. "People who seek high office often have certain character traits. They are risk taking, cool under pressure and narcissistic. When they have setbacks those traits are still there," she explains.

"It may seem like career rebuilding to us, but their egos lead them to think that they are just continuing to propel themselves, even if it seems to us like a hopeless case. Sometimes they feel as if it's their whole lives they're trying to cling to."

Public displays of humility are sometimes a necessary pre-condition to comebacks, even if they seem perfunctory. Early in 2005, David Blunkett, who had been sacked as Home Secretary in the fallout over his affair with Kimberly Quinn, ate humble pie and said that he needed to "earn" his comeback.

Earn it he may have done, yet just six months after returning to the cabinet as Work and Pensions Secretary, he was forced to resign again amid controversy over his ownership of shares in the biosciences sector.

Rumours are currently circulating Westminster that Brown intends to further reinforce the heavyweight credentials of his cabinet by again bringing Blunkett back into to the fold. Like Mandelson, he may benefi t from perhaps the most crucial factor in any comeback - timing. In uncertain times, even unpopular or divisive figures can find favour again if they seem to represent competence and certainty.

Lucy Beresford agrees that the right circumstances are crucial. "The chances of a successful comeback are partly determined by personalities and partly by outside factors, which certainly includes timing," she says.

"Even people who don't generally have the time of day for Peter Mandelson see him as something of a cheeky chappy after his comeback. It might not last, but sometimes you can just capture the moment."

Those Comebacks That Did Work

Silvio Berlusconi

In the hothouse of Italian politics, none are hotter than Berlusconi - whose latest comeback has seen him return to power for the third time, despite being widely regarded as a blunder-prone populist.

Harriet Harman

A year into the first Blair government she was dropped as Social Security Secretary after a series of public disagreements with Frank Field. Returning to the cabinet under Brown, she is now Leader of the Commons, Women and Equalities Minister and Deputy Leader of the Labour Party.

Richard Nixon

In 1960 he was the clammy antithesis of the optimism represented by Kennedy. Eight years later, he was a beacon of stability in a nation ill at ease with itself.

Those Comebacks That Didn't Work

Jeffrey Archer

The former Cabinet Minister and bestsellingauthor may be a king of comebacks, but David Cameron has made it pretty clear that he won't be making any more of them as a Tory.

Pauline Hanson

Her rightwing One Nation party shot to prominence in Australia before publicly imploding. Despite her eventual acquittal on fraud charges, the new Pauline's United Australia Party seems unlikely to march into government.

Simon Thomas

After losing Ceredigion in 2005, the former Plaid Cymru MP sought a high placing on his party's list for the Assembly Elections in 2007. He didn't get it and he wasn't elected.

Paul Evans is a freelance journalist