Further adventures in prestige for presidential hopeful Donald Trump, who has announced his membership of perhaps the least exclusive gentleman’s club in his collection: Guys Who Reckon They Could Totally Have Slept With Princess Di. Though this establishment tends not to be listed in their Who’s Who entries, for a certain generation of big-hitting men it is somewhere to feel like you’ve made it (just not with Princess Di). Such are the badges of achievement: black Amex, private jet, story about how Diana would have given you one but for whatever reason, didn’t.

In comments made soon after the princess’s death in 1997, unearthed again this week, Trump told the US radio host Howard Stern not just that he would have, but that he could have. “Why do people think it’s egotistical of you to say you could have gotten with Lady Di?” wondered Stern, masterfully. “You could’ve gotten her, right? You could have nailed her?” “I think I could have,” agreed Trump.

Or, as Princess Di’s friend Selina Scott last year recalled of Trump’s serial flower-bombing of Diana, “It had begun to feel as if Trump was stalking her”. “He gives me the creeps,” Diana told Scott. Given the sensitivities, it is notable to find Trump speaking so unguardedly to Stern so soon after Diana’s death. Still, perhaps he drew strength from the knowledge that if he couldn’t have her, nor could anyone else now.

And heaven knows, there was competition from fellow club members while Diana was still alive. No chap’s political memoir of the period is complete without the setpiece in which the princess flirts meaningfully with him or his boss. You have to write it carefully, of course, out of respect, but the reader ought to be left in no doubt that, had things been different in some tantalisingly unspecified way, she would have had it off with them. Even at the inquest into her death, Mohamed Al Fayed’s QC took the opportunity to read an extract from Alastair Campbell’s diaries, in which Tony Blair’s flirting with Diana at a dinner party was detailed. Not that Campbell himself was off the menu. He also takes the trouble to record the postprandial exchange with his wife, Fiona Millar, in which he asks her what she thinks Diana is after. “You,” is the reply.

‘The great lacuna in all these accounts is the bit where the men explain why Diana never seals the deal.’

As for how you could be sure she’d have had you even though she actually didn’t, some men were public-spirited enough to let you inside their process. The former French president, Valéry Giscard D’Estaing, once explained to a magazine how Diana let you know. Apparently, when Giscard was boring her to death at some banquet – I paraphrase slightly – “she leaned her head forward and lifted those immense blue eyes. That is the moment when you discover she is also a cat, a feline.”

Indeed, she was a pussycat of international reach. Reading the declassified transcripts of all those phone calls between Bill Clinton and Blair a few weeks ago, I got to the ones made in the immediate wake of Diana’s death. Despite Clinton’s declaration that “I just feel so bad for her”, it seemed as if the worst part of the tragedy for Bubba was that she’d now never get the chance to have sex with him.

‘Despite Bill Clinton’s declaration that ‘I just feel so bad for her’, it seemed as if the worst part of the tragedy for Bubba was that she’d now never get the chance to have sex with him.’ Photograph: Alamy

In other cases, the chaps are generous enough to compliment Diana on her notional choice of them. Take Dustin Hoffman, who had a sitdown (though not a lie-down) with her at a west London tennis club. “She was very proper until she turned to go,” Hoffman later recalled, “and she [looked back over her shoulder and made flirty eyes]. I thought, ‘That’s my kinda girl.’ It’s more fun to go through life that way, otherwise there’s a lie in the air.” Well quite. She knew she wanted it, and at least she had the honesty to admit it. Tacitly.

The great lacuna in all these accounts is the bit where the men explain why, despite obviously desiring them, Diana never seals the deal. And this is easily the most fascinating of all the Diana conspiracy theories: who or what were the mysterious but clearly immensely powerful forces that prevented her from going to bed with people like Trump?

Perhaps it has something to do with what the Queen reportedly said to Diana’s former butler, Paul Burrell, in a meeting shortly after her death. “Be careful, Paul,” Her Maj is supposed to have warned the future Celebrity Big Brother contestant, “there are powers at work in this country of which we have no knowledge.” Is this why Diana didn’t do it with Alastair Campbell? You’d be mad to rule it out.

Then again, anthropologist Desmond Morris was on hand to explain, of Diana: “When a young woman is in love, the condition affects the expression – her look and smile. It’s difficult to explain scientifically but we all recognise it. For most women, this expression is reserved for the loved one – but the curious thing about Princess Diana is that she has it whenever she’s happy. It’s as though she’s having a love affair with everybody. You can’t fake it – and it’s a signal that it’s impossible not to respond to. You can’t fight anything so basic.”

Thanking you, science, which in this instance feels way more emotionally speculative than even Candle in the Wind. All we can hope is that the campaign trail offers Donald Trump at least one opportunity to reaffirm Diana’s status as the one that got away, as she did for so many muscular power players of the age.