It promised much — a candid, soul-baring encounter between a psychiatrist skilled in the probing of great minds and a political grandee seasoned by life’s storms. Both men have their demons: the former tainted by scandal, the latter one of many ensnared in the parliamentary expenses affair.

This was an In the Psychiatrist’s Chair event at the Edinburgh International Book Festival, sponsored by The Times and The Sunday Times, that pitted Dr Raj Persaud, who formerly presented a BBC radio show of the same name, and Sir Menzies Campbell, the former leader of the Liberal Democrats.

“May I call you Ming?”, the doctor asked. Ah, not Sir Ming. Intimacy is established and the audience leant, metaphorically, forward like so many priests in a very large confessional.

We heard how Charles Kennedy was skilled at hiding his alcoholism, and that Tony Blair is so accomplished as a politician that he will probably avoid blame in the forthcoming Chilcot inquiry into the Iraq war.

We discovered how it felt to run in the relay final at the 1964 Tokyo Olympics. A moment of joy, then?

“My abiding memory of it was I might drop the baton,” he said. A dropped baton. The inner psychiatrist in all of us made a discreet note.

We also heard Sir Ming’s account of his first encounter with Major General Roy Urquhart, his future father-in-law, and the formidable former leader of British forces at the Battle of Arnhem.

Major General Urquhart had raised three points: “Are you sure it’s not physical infatuation?”; “Elspeth is no spring chicken, you know”; and “I’m not paying for a second wedding.”

Dr Persaud could have said: “That probably scarred you for life?” But he didn’t, good doctor that he is.

And so we waited, pencils poised, for that moment of confrontation, of a challenge to the very soul. But sometimes it takes more than one session.