The telephone call came out of the blue one Monday lunchtime. “I’m going,” announced Sir Menzies Campbell.

“At Christmas?” asked his wife Elspeth, taken aback, although she was aware that he had not had the easiest of weeks.

“No, today – I’m flying back [to Edinburgh] this afternoon,” said the 66-year-old Liberal Democrat leader.

“But there’s nothing in the fridge,” she protested, momentarily thrown off course.

It’s four months since Campbell (known as Ming) stepped down as leader of the Lib Dems. But it is only now that his elegant – and occasionally formidable – wife Lady Campbell is prepared to talk about her husband’s tempestuous time as leader, his resignation and their lives today.

“I think I could have leant on Ming and said, ‘Don’t do it’, but I didn’t feel that was the right thing to do,” she says. “The alternative would have been to stay and fight, although I don’t think it would have been good for him or the party. I wanted him to choose the moment of leaving . . . and that’s what he did.”

We are sitting in the dining room of her smart Georgian town house in the West End of Edinburgh, where everyone from Sir Malcolm Rifkind, the Conservative former foreign secretary, to Jack McConnell, the Labour former first minister of Scotland, and Ian Rankin, the bestselling author, has at one time or another been a guest of the Campbells.

Ming Campbell’s reputation was arguably at its highest when he was the Lib Dem foreign affairs spokesman, and there is no denying that he had a tough time as party leader before finally stepping down last October after just 20 months in the job.

Up against a young and dynamic new Conservative leader, he suffered by comparison – particularly at prime minister’s questions, where his performances were somewhat patchy. Rumours of internal dissent began to surface – and then, of course, there was “the age issue”.

So what does Lady Campbell – whose father, Major-General Roy Urquhart, commanded the British troops at Arnhem – think finally did for Ming? Was he “knifed” by one of his own or was he simply deemed too old?

“The party’s support was absolutely constant,” she insists. “Yes, there were some unhelpful comments, but those were usually attributed to unnamed Liberal Democrats. No one went on record attacking him.

“The press also played its part in his downfall: he couldn’t escape that constant sniping about his age. I sometimes gave up reading the papers, I found it so depressing. And I felt it was so unjustified. Look at John McCain!

“If Gordon Brown had gone ahead and called an election last autumn, though, Ming would not have resigned. There was a plane on stand-by. A flat in London. He was looking forward to it; he was ready for a fight.”

Could it be that Ming, whose manner has been compared with that of Harold Macmillan, the former prime minister, was just too much of a gentleman in an era of spin doctors and 24-hour rolling news?

“I can see why people might think that, but he’s by no means a walk-over. He’s pretty tough,” says Elspeth Campbell, who became his wife in 1970 following an unhappy first marriage to Sir Philip Grant-Suttie by whom she had a son, James.

“Ming took all that flak for 20 months and he often said to me, ‘I can do this job if people just let me get on with it’.” She pauses a moment to light a cigarette. “But there’s no doubt that that sort of cut and thrust – the bitching and the backbiting – didn’t suit his style. If people were critical of him, he’d have expected them to come to his office and say it to his face. He wasn’t prepared to fight down and dirty.”

Almost as an afterthought, she adds: “I often wonder, if he’d had an Alastair Campbell-type figure advising him from the beginning, whether he could have knocked all that ageism on the head from day one.”

If there is a moral to the tale, it’s perhaps that politics, at least in Britain, is a young – or relatively young – man’s game.

“If that is the case, it’s a sad, sad thing,” says Elspeth Campbell, who is herself aged 68. “Being young and charismatic seems to be an obsession these days. It’s the same in America to an extent – look at Barack Obama. He’s young and inexperienced, but he’s charismatic and has the gift of the gab.”

A bit like Nick Clegg, Ming’s successor? “Actually, I’m a big fan of Nick’s,” she says. “I think he’s doing jolly well. He comes across well. He looks right – even if he does look so young. ”

What, then, of the “handbagging” that she famously gave Clegg at the last Lib Dem conference, when he admitted to having leadership ambitions of his own?

“That’s history,” she says, with a throaty laugh. “Actually, I thought I’d spoken to him in a friendly fashion. And whenever we see each other now we have a laugh about it. It’s one of those things that got blown up out of all proportion. Ming voted for him, though.”

She looks reflective. “The truth is that if you’re well into your sixties, I think you’ve probably had it if you want to lead a political party in this country nowadays.”

One of the first people to call up to offer his sympathy last October was Sir John Major. “John Major is one of my pin-ups,” she says, chuckling again. “He said, ‘I know how you feel – I’ve been through this’.”

Charles Kennedy, the former Lib Dem leader, was also quick to offer his support – a gesture much appreciated by Elspeth Campbell, who confesses that she burst into tears when Kennedy himself quit as leader.

“Contrary to what has been said, I never saw any evidence of animosity towards Ming on Charles’s part,” she adds. “And they continued to have lunch together on a regular basis to discuss things even after [Kennedy] resigned.”

Since Ming stepped down, she admits, “some of the excitement has been removed. One was living on the high wire – and I miss that to an extent. I miss going to state banquets at Buckingham Palace and taking part in the Remembrance Sunday commemorations at the Cenotaph. That always meant a lot to me”.

On the other hand, she certainly doesn’t miss her husband’s gruelling weekly confrontations at prime minister’s questions, which she says were “always something of an ordeal”.

“Whenever I watched, my heart was in my mouth. Funnily enough, though, both Tony Blair and David Cameron told Ming that it was the most dreadful event of the week for them, too, and [both] confessed to feeling sick beforehand. I’m sure Gordon Brown finds it every bit as testing. You can tell that by looking at him.”

As for Ming, he has been finishing off his memoirs which will be published next month. The bulk of the book had already been written when he became leader, but he has since updated it. Will it be explosive?

“I’m sworn to secrecy,” says Elspeth Campbell wryly. “But it’s a rags-to-riches tale, in a manner of speaking. The part I found most moving was when he talks about the cancer he suffered from a few years ago, when it really was a matter of life or death. An illness like that puts everything in perspective.”

She is pleased that Ming wants to stand again as an MP at the next election and delighted that he now has more time for his grandchildren – his stepson’s three boys, aged 8-16. “You’ve got to remember that he took on my son James when he was five – and treated him like a son. They’ve always got on extraordinarily well.

“The oldest [grandchild] is actually going to do politics for his A-levels and that’s largely down to Ming.”

Might he, too, go into politics some day? “I think he might,” she says.

Fighting as a Lib Dem? “Hopefully,” she says, with another laugh, “although it might not be a very wise career move.”

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