The careers​ of politicians do not always end when they were supposed to. The Duke of Portland resigned as prime minister in 1783, only to have another, more successful go at governing 24 years later. Gladstone retired from the leadership of the Liberal Party in 1874 aged 65, but was leader and prime minister again by 1880, and quit his fourth premiership on a point of principle in 1894 aged 84, impatient, indignant, and half-blinded by a ginger biscuit thrown at him by an angry woman during a rally in Chester. Arthur Balfour led the Conservatives to their worst ever election defeat in 1906, losing his own seat in the process, but served as foreign secretary during the First World War and was still in the cabinet in 1929, 55 years after he first entered Parliament. Winston Churchill was elected in 1900 as a Tory, became a Liberal, lost his seat, got another one, became a Tory again, won the premiership, lost it, and won it back again, retiring from Parliament in 1964. Even Alec Douglas-Home had a second act after losing the election of 1964, serving as foreign secretary under Edward Heath.

These are the lucky ones. A different fate awaited Jim Callaghan, who drifted into a burdensome obscurity after losing the 1979 election and resigning as Labour leader the following year. There is a sad letter from him in the LRB archive, responding in 1991 to a piece by Ross McKibbin praising his and Harold Wilson’s record in government: ‘it is rather nice,’ he wrote, ‘to cease to be a kind of non-person.’ Still, for all the pathos, Callaghan was 68 when he resigned in 1980, the only man to have held all four of the great offices of state, and had been in Parliament since 1945. It wasn’t a bad effort.

Longevity is increasingly rare in British politics. We have got used to political careers coming abruptly to a halt, defeated prime ministers leaving Parliament after a short interval (hours for Blair, five years for Major and Brown, with Cameron likely to follow suit) and party leaders quickly throwing in the towel after election defeats (Hague, Miliband, Clegg). The most recent generation of political leaders attained high office infinitely faster than their predecessors, serving no serious apprenticeship in Parliament or government, and their fall from grace has been far steeper as a result. Cameron was elected to Parliament in 2001 and became leader of the Tories in 2005; Nick Clegg and Ed Miliband were both elected in 2005 and became leaders of their respective parties in 2007 and 2010. They are all now relegated to the back benches, all aged under fifty.

They are still in Parliament, at least for now, unlike Ed Balls. First elected in 2005, he served in the cabinet for three years until 2010, followed by five years as Miliband’s shadow chancellor, before losing his seat last May aged 48. His defeat, announced at 7 a.m., was the perfect conclusion to Labour’s terrible night: the man the polls predicted would be setting the next Budget was instead out on his ear. Now, a year on, in addition to becoming a lecturer at Harvard and chairman of Norwich City, he is a contestant on Strictly Come Dancing: ‘a dream come true’ for him, and also presumably for his publisher.

Balls became an economic adviser to Gordon Brown aged 27 after a few years at the Financial Times, becoming Treasury chief adviser after 1997. It was not until he’d spent more than a decade at the top of politics that he became an MP, so that reading his autobiography, Speaking Out: Lessons in Life and Politics (Hutchinson, £20), one has the strange impression of his career slowing down at exactly the point you’d expect it to get started, as he leaves behind the international summits and the dramas of Budget day, to become bogged down in the prosaic duties of constituency work, taking on cabinet responsibility as secretary of state for schools, children and families and as a consequence being separated from Brown when he finally reached Downing Street in 2007 (Brown initially asked him to take over the chancellorship, but withdrew the offer for fear it would provoke opposition from the Blairites).

Ed Miliband too was an adviser to Brown at the Treasury, was elected in 2005 and joined the cabinet in 2008 at the head of the department for energy and climate change. Peter Mandelson, David Miliband, James Purnell and Andy Burnham were other New Labour luminaries who swapped being special advisers for being parliamentarians, all of them, like Balls, dropped into carefully selected safe seats (Balls reveals that he put pressure on his predecessor as MP for Normanton not to resign ‘prematurely’ in 2001, ‘as I still had the euro assessment to oversee’). Policy wonks proficient in the dark art of internecine warfare, none can be said to have made a great success of their second careers. Too many years spent in the shadow of Blair and Brown had done for them.

Balls’s appearance on Strictly Come Dancing is the latest in a series of well-publicised attempts to show that he too, borrowing Denis Healey’s phrase, has a ‘hinterland’. The interests we’ve been told of include marathon-running, baking cakes and making spaghetti bolognaise: Healey’s reputation is safe. But Balls has also gone public about his struggle with a stammer, and earned affection for his good-humoured response to the Twitter phenomenon that is ‘Ed Balls Day’, celebrated worldwide on 28 April to mark the anniversary of the occasion when he accidentally tweeted his own name. (His name gifted the Tory Conference one of its less feeble jokes when it was revealed that Balls had inserted the phrase ‘post-neoclassical endogenous growth theory’ into one of Brown’s speeches: ‘It’s not Brown’s, it’s Balls,’ Michael Heseltine wisecracked.)

‘What I learned,’ Balls writes in his autobiography, ‘was not only that [my] new hinterland activities were helping me to manage my midlife crisis … My new passions added an extra dimension to my communication with the public, and, from what they said to me in response, changed a few minds.’ Strictly, he has told anyone who will listen, will prove that politicians are ‘human’ too, and in his media appearances leading up to the live shows Balls has been twinkly, smiley, open-necked, making jokes about needing to lose weight and his hips not moving in the right way for the cha-cha-cha. If he continues to dance as badly as he did in his first live appearance, he will be a national treasure by Christmas.