Some things were just never meant to be common knowledge. I read with a wince this week an interview with the BBC's royal correspondent Jennie Bond in which she revealed that she occasionally goes commando.

For those of you now scratching your heads wondering why she feels the need to don combat gear while snaking along enemy lines on her stomach, let me explain that "going commando" doesn't mean she's in the TA, it means she occasionally likes to venture out while her knickers enjoy a quiet night at home alone.

I suppose we are used to seeing Nicholas Witchell and Nicholas Owen on our TV screens, so why not Knickerless Bond?

It is not as if she is ever likely to give us a quick flash when signing off outside Buck House, or do a Sharon Stone while interviewing Prince Edward about his latest cock-up.

You see, I really don't have a problem at all with Jennie going knickerless on the news - she and Michael Buerk could be wearing each other's grundies under the desk for all I care - but I do object to her telling us about it.

There are some things that the public just doesn't need to know. And conversely, of course, there are some things we do.

I believe, for example, that we need to know whether baby Blair has had the MMR jab. It is a simple question and it deserves a simple answer.

The Prime Minister and his wife have tried to complicate the issue by turning it into a debate about privacy, but this is nothing more than a crass avoidance tactic.

Whether by design or by default, the Blairs have carved out a niche for themselves as Britain's first family and as such have given up their right to be coy on issues of national interest.

Shortly after coming to power, Mr Blair was quizzed on his and Cherie's choice of school for their children. Just as it was important then for us to know whether public sector education was good enough for Euan, Nick and Catherine, it is important for us to know now whether the MMR vaccine is safe enough for little Leo.

Going by the Prime Minister's mincing hints on the subject, I think it is safe to assume that the youngest Blair has had the jab, but that is not good enough. We need him to actually tell us that he has.

At the end of the day this is not a debate about Leo's private medical record, it is about the honesty and credibility of Tony Blair and his Government. If he simply told us one way or the other it would at least give the impression of openness.

Parents are being berated for asking reasonable questions; they are, in effect, being treated like children. Whether their fears are justified or not, they feel they are being ignored.

It is not enough for the Government to tell parents to have their children vaccinated "because we say so". They need to be convinced not corralled into making a decision, they need firm evidence gleaned from scientific research carried out in this country and, in the meantime, they need to be given the choice of single jabs over the triple dose.

After the BSE debacle when we were told British beef was safe one minute and potentially deadly the next, it shouldn't come as any big surprise to the Government that the public needs more convincing on a subject as fundamentally divisive as MMR.

And while we are not asking Mr Blair to do a full-on John Gummer-style rave about the joys of inoculation (I wonder if that poor child can so much as glance at a beef burger without breaking out into a cold sweat), it would be a commendable act of camaraderie if he simply said it was safe enough for Leo.

And just so I don't fall into the Blair trap on this issue, let me tell you that my son has had the MMR jab.

Oh, and I am wearing knickers.

Updated: 10:14 Tuesday, February 12, 2002