If being Prime Minister is inevitably the toughest job in British politics, then being a former Prime Minister is surely not that far behind.
Of the three surviving bearers of the title, the only one who has made anything approaching a decent fist of it over the course of recent years is that much under-rated figure, Sir John Major.
I will never forget his quiet dignity in defeat on that bright May morning in 1997 when he spoke of curtains falling and actors leaving the stage before going off to watch some cricket at The Oval.
And he has continued to be dignity personified throughout the ensuing years, never once succumbing to the temptation to criticise any of his many successors as Tory leader and only ever intervening in a way helpful to his own party.
In this, Sir John was determined not to follow the example of his predecessor Margaret Thatcher, who made clear her own intentions shortly after he succeeded her by declaring her skill at back-seat driving.
The Iron Lady, who was finally laid to rest this week, clearly found being an ex-Prime Minister rather harder to come to terms with than the actual job itself.
So, it seems, has Gordon Brown. When he lost the premiership in 2010, those of us who still counted ourselves among his admirers hoped he would rebuild his reputation by becoming a good constituency MP and backbench elder statesman.
Unfortunately, he has veered off into the biggest political sulk since Edward Heath’s, barely ever turning up at the Commons and, save for a rather self-justificatory attack on Rupert Murdoch, saying almost nothing of any value since leaving Number Ten.
But the former Prime Minister whose post-Downing Street career provides the greatest fascination, for me at any rate, is surely Tony Blair.
Aged just 54 when he left office in 2007, it was never remotely likely that the former Sedgefield MP would go gently into that good night as Sir John had done ten years earlier, and some sort of comeback was always on the cards.
For a time, this looked likely to be at European level, with the presidency of the European Council of Ministers the most obvious potential destination.
But thwarted in that ambition by the surprise elevation of Herman van Rompuy, his attentions have turned back to domestic politics and, specifically, the future of the Labour Party.
Mr Blair took to the pages of Labour house journal The New Statesman to warn party leader Ed Miliband that his opposition to welfare reform and spending cuts risked reducing Labour to a party of protest.
In another recent intervention, he declared that the result of the last election would have been closer had he still been leader, thereby implying that the party’s chances of winning in 2015 depend on the extent to which it stays true to his legacy.
This, incidentally, is poppycock. Whatever Mr Brown’s failings, had Mr Blair gone on and on and attempted to win a fourth consecutive term in the teeth of a recession, and with the baggage of Iraq still hung around his shoulders, he would have gone down to a landslide of 1997 proportions.
But no matter. Blair is back, and it is clear that the younger Miliband had better get used to the fact.
For now, the party leader’s stock response has been to turn Mr Blair’s own revisionist methodology against him, saying: “Tony Blair taught us the world changes. The world does change and we will learn our lessons."
But while this is undoubtedly true, he will eventually have to explain in much more detail how the Labour Party under his leadership has responded to those changes.
Over the past couple of weeks, Prime Minister David Cameron has had to suffer the inevitable unhelpful comparisons with an illustrious predecessor who won three straight election victories where he could only manage a hung Parliament.
Mr Miliband’s chances of going one better may well depend on how far, if at all, he can escape from Mr Blair’s long shadow.