It can be cruel, the way politics plays out. At the very moment George Osborne was telling the bemused staff of the London Evening Standard last week that his working life in politics had obscured a passionate desire to become a newspaper editor, a familiar figure could be seen in the fresh meat department of the Whole Foods supermarket almost directly underneath the paper’s Kensington newsroom.

That man was David Cameron, and inevitably someone with journalistic instincts spotted him, snapped him on her phone, and tweeted it.

Stephen Robinson and James Forsyth discuss Cameron and Osborne's diverging retirement plans:

We congratulate ourselves on the ‘here today, gone tomorrow’ nature of British politics. So it is a healthy sign that there is an informality about the man described by the Washington Speakers Bureau, the agency which now organises Cameron’s lucrative global lecture schedule, as ‘one of the most prominent global influencers of the early 21st century’.

If he volunteers to do the family shop, that reflects well on him, and by extension us. There is nevertheless a poignancy in the juxtaposition of Osborne cementing his position with a newspaper editorship while his former boss is still searching for a role.

‘The problem is that David can’t really fill his day,’ says someone who knows him well. An old friend, who now sees less of him than he did, adds: ‘Dave found he was really good at the mechanics of being Prime Minister, and loved almost every minute of it. Obviously it leaves a hole.’

After he left Downing Street at the age of 49 last summer, Cameron had unrealistic expectations of the world beyond politics. ‘He would ring up mates and suggest a game of lunchtime tennis,’ recalls a friend. ‘I’m afraid he’d get the answer: “Sorry, can’t make it; I have a job.’’ ’

Perhaps because he was born into money, and then married into even more of it, Cameron has never appeared to worry too much about accumulating wealth. Another friend says he feels aggrieved that George Osborne is hoovering up more than his fair share of the potential earnings of deposed Cabinet members.

Osborne is showing true New Labour zeal in flaunting how intensely relaxed he is at becoming filthy rich. With his recent BlackRock contract (£650,000 a year for one day a week, plus future stock options, plus speeches at £80,000 a go), Osborne is already well-insulated from any delayed manifestation of Project Fear. And his latest role as editor of the Standard, which will add another £300,000 or so to the pot, gives him a platform from which influence the political debate.

Cameron, by contrast, has taken honorary leadership roles at an Alzheimer’s charity and at the National Citizen Service. To put bread on the table, he has also made some lucrative speeches. Now he has left the Commons he does not have to report his earnings publicly. This week he has been in America doing lectures, and at Davos he spoke at a lunch held by Viktor Pinchuk, a Ukrainian billionaire.

As a former prime minister he has appeal, but in the long run the big money on the lecture circuit is in speaking to banks and hedge funds, where Osborne’s experience as Chancellor guarantees top dollar.

Cameron tells his friends that he has one more ‘big job’ in him, but it is difficult to see what that might be. Aside from a spell at Carlton Communications, he has scant corporate experience. Brexit has obviously destroyed any prospects of him or any other Briton securing a big job in Brussels.

A year ago, the top job at Nato would have seemed a good fit for a British elder statesman. The Norwegian Jens Stoltenberg is due to step down next year, but it seems unlikely that European Nato members will accept as secretary-general the man who triggered the break-up of the EU.

This leaves Cameron with a book to write, and according to members of his circle, it is heavy going. Few politicians, even those with first-class Oxford degrees in PPE, write very well.

Cameron, according to a friend, was initially gung-ho about his memoir. He went along in person to some of the pitches to reassure publishers that his book would not be a ghost-written trot around the block. He secured an £800,000 advance, which might be rated a bit of a disappointment, certainly compared to the $60 million Barack and Michelle Obama are reported to have secured for their autobiographies.

The problem is that unless Cameron is prepared to settle scores and wash dirty linen, it is difficult to see how his memoir will fly off the shelves. Thatcher and Blair had a guaranteed book-buying audience in America. That cannot be said of Cameron.

By all accounts, the writing has proved a trial for him. Jacob Rothschild has helped him with an office in St James’s, but Cameron prefers to go to the weekend home in Oxfordshire to write, or to his wife’s family estate in Yorkshire.

It turns out that the principal victims of Brexit are the game birds of North Yorkshire and Oxfordshire, for Cameron is back out with his shotgun, having taken a break for presentational reasons during his Downing Street years. ‘His inner toff is coming to the fore now he is out of office,’ says an associate who speculates whether the old Bullingdon Club photographs will be coming down from the attic.

One habitué of St James’s says Cameron is once again a regular luncher at White’s, the club from which he resigned in showy protest at its non-inclusive membership rules. His son is reported to have been considering St Paul’s Juniors, so the only question now may be whether the boy goes on to a private London day school or to Eton.

Samantha says she won’t allow ‘politics’ to influence her children’s education, which is what wives say when they want to give their husbands the political cover to climb down from expedient positions. It is safe to assume that state education is now off the agenda for all three children.

While Samantha Cameron’s outlook remains very London-focused, with her fashion label, friends report David’s centre of gravity has shifted slightly back to Oxfordshire. The Brexit furore has triggered a breach with some of his old friends, most spectacularly Michael Gove. Generally, Cameron sees less of his Notting Hill friends and more of the county set, though word is that the Chipping Norton gang of Jeremy Clarkson, Rebekah Brooks et al are not as thick as they were.

It was striking how few of the 20 or so guests at his 50th birthday party in the autumn were from the political world. Dinner was cooked in the family Aga by the property developer and Tory donor Tony Gallagher, an Oxfordshire neighbour, but there was no room for his newly knighted former press man Craig Oliver or many other close political associates.

Cameron has not been able to shake off the humiliation in political circles of the Brexit defeat, or forgive those on the other side of the argument. Thus, the most curious omission from his birthday guest list was Anthony Bamford, a friend and generous party donor who never concealed his Brexit sympathies.

It would be wrong to suggest that Cameron has sunk into a post-Downing Street funk. That is not his nature. He is, friends say, an optimist who almost all his political life was blessed with amazing good luck.

But those who know him well — or in some cases, knew him well — say he is not firing on all cylinders. He has always been something of a dilettante, for whom politics was a bit of a parlour game between Eton and Oxford friends.

Had Boris Johnson met political oblivion after Brexit, he’d have banged out his memoirs in three weeks and moved on; Cameron cannot show such ruthless zeal. Meanwhile, his abrupt decision to leave the Commons has deprived him of a daily structure and of a political platform where he could have influenced the implementation of Brexit. ‘It was proving excruciating to remain in the Commons,’ says a friend, ‘because anything he said was misinterpreted. But it has left a gap.’

Paul Dacre, the Daily Mail editor, never really saw the point of David Cameron, an animus redoubled when it was recently reported Cameron had tried to get him sacked before the referendum. From time to time, Dacre would drop in at Downing Street to catch up on politics over an early evening drink. Then Dacre would head back to the Mail office to oversee the first edition proofs, telling subordinates of his amazement that he had left the Prime Minister with his feet up having settled in for the night with a boxset of Scandi noir.

Some fear that an absence of a strong work ethic, and his tendency to ‘chillax’ over a glass or three of wine, does not lend itself to a post-Downing Street portfolio existence.

When evicted from Downing Street last year, Cameron was five years younger than Ted Heath and Margaret Thatcher when they arrived there. The young man who always seemed to be in a hurry has been left with a lot of time to ponder how he will be remembered.