It wasn’t until the end of an hour or so with the Labour Party’s elder statesman — “Elder, certainly,” was his response, when I asked whether that’s how he saw himself — that I was emboldened to serenade Lord Healey thus: “Remember my interview with Denis Healey/ When he came over all touchy-feely/ Saying ‘What a shame, no time for rumpy-pumpy’/ Which made me laugh/ Which made him grumpy . . .”

“Very nice. Thank you, dear,” he said, clearing his throat.

This was from a song I wrote for the Petronella Wyatt character in last year’s Soho showcase of David Blunkett The Musical. She earned her role as one of the dramatis personae because of her own rumpy-pumpy relations with Boris Johnson — part of the Sextator quartet subplot — but the lines were inspired by her coquettish copy as a famously flirtatious interviewer at The Daily Telegraph. Her charms clearly brought out Lord Healey’s inner goat back then (the rumpy-pumpy line was allegedly his parting shot to Petsy), but now he is not entirely sure whether Petronella is Woodrow’s widow or daughter.

The mental filing cabinet may not be as orderly as it once was — his memory started fading at 75, he says, from the vantage point of an 88-year-old — but Lord Healey’s entrances as well as his exits remain as frisky as ever. After asking me to pose for a photograph — a request that he has put to several interviewers in recent years, the female ones at any rate — he growls “Take your clothes off” into my tape recorder. This would have been more startling if I hadn’t read about the opening gambit before. It’s rather touching, really, that he still bothers to make the effort.

While he is often described as “the best prime minster we never had” and sometimes as “the man who saved the Labour Party” (when he fought the bitter battle against Tony Benn in 1981, narrowly defeating him to become deputy leader to Michael Foot), Healey seems to be a figure who is compelling nowadays more because of the success of his long and fruitful marriage to his writer wife, Edna, than for his impact on the political landscape of half a century of postwar Britain (the history of which is covered in his exhaustive, and occasionally exhausting, 1989 memoir The Time of My Life, which has been recently reissued with a new afterword).

We talk in one of the spacious, light-flooded reception rooms of the Healey residence in the village of Alfriston, which sits substantially at the top of a winding drive and looks over the Sussex Downs. We have had several short telephone conversations over the preceding weeks, prompted by Lord Healey’s concern that we have the right date and time. When I arrive he is at the door, looking a little anxious and a little relieved, the robust frame and jowly good looks of his much-photographed middle age now somewhat etiolated. But he stands unbowed and is dressed partly youthfully in trainers (not Converse, thankfully) and a slightly eccentric, sort of Ian Fleming Out of Africa short-sleeved safari jacket. The killer eyebrows still bristle luxuriantly but the eyes beneath them burn less brilliantly.

Healey’s manner during the interview could hardly be sweeter but he also seems a bit distracted, partly because he is quite deaf; many of my questions (I have a booming voice) are met with a polite but quaint “Pardon?”.

Behind the table at which we sit, covered with albums of Healey snaps of friends and family, is a giant black and white photograph of Edna. She looks so young and somehow questing, standing in snow at the foot of an icy cave. The expression on her face is entrancing. I have the sense of her watching protectively over the proceedings as though she were no longer here when, in fact, she is sitting in the next room working away at her own writing. I am thinking that only a public figure so conspicuously happily married as her husband could afford to make such concupiscent verbal flourishes towards women journalists.

Since l’affaire Prescott is still very much in the air when we speak, I ask Healey what he makes of it: “Well, it’s a shame but that’s life, isn’t it? I mean, I like Pauline. I like John. And I’m very sad for Pauline, but if you’ve fallen in love with someone, that’s that — isn’t it?”

You’ve always said that it’s in the nature of political life that there’s enormous temptation to go astray. “Well, you tend to be separated too often from your wife, especially — thank God, it never was in my case — if she lives in a constituency 200 miles away.”

People get lonely? “They do, and they tend in the end to have affairs with their secretaries, don’t they?” But you were never tempted? “No, never. Never.”

I had always thought that it was Healey who had upbraided his fellow politicians for lacking “hinterland” — meaning that they had no other interests beyond politics and were therefore lacking as well-rounded human beings — so I’m surprised to discover in the memoir that it was Edna who first identified it as a flaw, in relation specifically to Margaret Thatcher. Lord Healey, at any rate, has always had hinterland in spades with his various passions for music, poetry and painting. He wrote in The Time of My Life: “Some of my friends complain that . . . I have far too much hinterland. My wife and family have always meant more to me than the House of Commons . . . nothing is more dangerous than the politician who uses politics as a surrogate for an unsatisfactory personal life.”

Among his favourite poets are Emily Dickinson, Yeats and Eliot — and he is devoted to Virginia Woolf, his “literary idol”.