When choosing our leaders, we need to build a stronger boundary between the personal and the political

Image matters when your husband is seeking election as prime minister. But it wasn't her frock that took my attention. Then, I was looking at a grieving young mother. It was October 2009 and her six-year-old son Ivan had died in February.

Those of us who have not lost a child can only guess at the wound it inflicts. Parents who have been through it say it is profound and lifelong. I'm sure it is. Ivan Cameron was the couple's first baby. He was born with a congenital disorder that required round-the-clock care.

Last weekend Samantha Cameron gave an in-depth magazine interview in which she spoke openly about Ivan's birth, about their distress when she and her husband learned of the boy's disability and about the effect it had on them and their family. She was frank about the challenges the couple faced and wept as she described how they were pushed to the limits. She told of her continuing grief and how she had counselling to help her cope.

It was moving to read. How could anyone not empathise with a mother talking about her lost child in terms like these? "He was very beautiful one of the great gifts in our lives. A day when you haven't been to hospital, a day when he smiled, or a day when you haven't cried, becomes the most amazing day. You get pride and joy out of the tiniest little kind of triumph. Ivan gave us that every day.'

So, it is clear that Ivan's life and death are a huge and no doubt formative part of the Camerons' marriage. And I'm sure her frankness and honesty will help many struggling parents. Impressed though I was by the interview, I wished it had not appeared in the run up to the General Election.

A similar thought came to me when David Cameron referred to Ivan when he was challenged about the National Health Service during the leaders' debate last week. There was a catch in his voice when he said he would not forget what he had received from NHS staff as the father of a disabled son in terms of "unbelievable" care and support.

It wasn't the first time I'd heard him cite his boy's treatment when speaking about the NHS. It's hardly surprising, you might think. Six years of crisis management with Ivan is the experience through which he best knows the health service. It's the experience that drives his commitment to it.

I accept that but I am beginning to feel a bit queasy about being reminded of it.

I don't doubt the Camerons' sincerity. It is perfectly right and proper that they should keep their son's memory alive by talking about him in the same way they do of their other children. As Mrs Cameron made clear, Ivan remains central to their family.

So why did I find myself wincing when Mr Cameron made the reference during the leadership debate? I think it was because this was the first major round of battle in the election campaign so there was a danger that his reminiscence could be seen as a tactic.

It feels harsh just writing that but it could be viewed that way.

Mr Cameron has also spoken about his other children, especially Nancy. He has been known to jest about his oversight in leaving her behind in a pub after a family lunch outing. Samantha Cameron's weekend interview displayed a large photograph of his younger daughter Florence sitting in a red dispatch box and one of Nancy and her brother Elwen standing outside Number 10 Downing Street.

But it is because Ivan's story is so affecting that there is a danger it could be perceived as a means of gaining a sympathy vote from the public. The parents may be unaware of this but I do wonder about their advisors. I wonder why they haven't flagged up that speaking about the couple's private grief during the cut-and-thrust of an election campaign is in danger of being misinterpreted.

Our last prime minister, Gordon Brown also lost his first born. Jennifer Jane Brown was born in December 2001 and lived for only a few weeks. In February 2010, in a rare interview on the subject, Gordon Brown described it as "the most grief stricken time of my life".

That interview too was moving; the pain expressed in it was clearly sincere. It, too, was just months before a general election.

I feel increasingly that, in choosing our leaders, we need to build a stronger boundary between the personal, especially when tragedies are involved, and the political. Mr Cameron has been Prime Minister for five years so, when people ask about cuts to services, isn't it his record and his plans for the English NHS's future, his plans for the country, we need to hear about?

When the electorate expresses anxiety that he is opening the way to increasing privatisation, don't they need hard facts rather than personal reassurance? They need to know that, when they or their loved ones seek medical help, it will be there for them with the staff and resources to offer a high standard of care.

Perhaps it is because the race to Downing Street is unpredictable that this General Election has seemed to focus so much on the personal. We have already been in Mr Cameron's kitchen with the BBC's James Landale. We've been for a walk with Ed Miliband, his wife and sons, which felt about as relaxed as a half hour in the dentist's chair. And we've seen the Labour leader pictured in what turned out to be his second kitchen, which was more like a scullery.

I sometimes fear we are heading into the territory of Saturday night television. Anyone who has watched The Voice or the X Factor will be familiar with the back story of the contestants. It isn't enough for aspiring singers to perform; the audience must also visit their home, meet their family and register the degree of passion with which they hope to win.

Presenting a domestic image of politicians isn't new. In the 1960s John Kennedy was pictured at his desk in the Oval Office with his toddler son John junior, sitting in the knee hole. Then, a less cynical public bought into the image of Camelot in the White House. It took decades to discover that the pin-up husband and father was a compulsive philanderer.

Margaret Thatcher let us see her shopping and cooking supper for her husband Dennis. Tony Blair strolled out of Downing Street to address the assembled press in shirtsleeves, carrying a mug decorated with a picture of his children.

Increasingly these insights look as contrived as images of Vladimir Putin bare-chested on horseback. Don't patronise us, I want to tell the television; don't try to manipulate our vote.

Above all, don't push fundamentally decent politicians into exposing too much. Their years in power are a short section of their lives. For that reason they need to protect what really matters to their families lest they become exploited in their political party's pursuit of power; and we, the electorate, are manipulated into muddling the family man with the politician.