Many, many years ago, a little girl called Harriet was bitterly disappointed on Christmas Day when, after ripping open all of her gifts, she discovered that she had not been given the pink Barbie camper van for which she had secretly yearned for many months.

But being the trooper that she is, young Harriet wiped away her tears and made a solemn promise to herself. One day, she whispered under her breath, one day when I’m all grown up, I’ll show them, I’ll give myself an even BETTER pink camper van.

I have no idea whether any of this actually happened to Harriet Harman as a child or not, but it is the only plausible explanation that I can come up with to explain the decision by the Labour deputy leader to hire a bright pink van as her not-so-secret weapon to take the election campaign directly to female voters on the streets of Britain.

Because there really isn’t any other reason why anyone over the age of, say, seven would think that the best way to take the Labour party’s message to 51% of the electorate was with a vivid pink van adorned with phallus-inspired arrows and the words “woman to woman” on its sides.

Harriet Harman had promised that women would be “at the front and centre” of Labour’s election campaign – and boy did she mean it. With bells on.

In stark contrast to the old Prescott battle bus, the Harriet-mobile bears a closer resemblance to Delboy Trotter’s three-wheeled yellow minivan than her predecessor’s big beast of a campaign bus.

Harriet’s dedicated women’s 16-seater van will nevertheless visit 70 constituencies before May, asking women what they want from a Labour government.

What could have been the strategic thinking behind this decision? A one-woman focus group inside Harriet’s head? “I’m a woman and I know women. Women like pink so if something is pink they’ll like that too.”

Apparently not, since both Ms Harman and Gloria De Piero MP, the shadow Minister for women and equalities, were insistent at Tuesday’s launch that the van was not in fact pink at all. It just looks it.

Ms de Piero was very sure that it was “cerise”, while Ms Harman was certain it was actually “magenta”.  The key thing was that it stood out from the traditional Labour red and it wasn’t a white van that was going to get them into more hot water with working class voters. Instead of white van man, we will get Not Actually Pink Van Woman.

The Labour deputy leader was insistent that the van wasn’t a darker red because it might get confused with a Pret A Manger delivery van. Still, better to risk being confused with a sandwich delivery service than Katie Price (aka Jordan)’s pink horse box, eh?

And she maintained that the van was not “patronising”, saying that the campaign would focus on vital issues like childcare, family care, equal pay and tackling domestic violence.

By all accounts, other more sensible types in the Labour hierarchy (no doubt those people who like the colour blue – you know who you are) tried in vain to talk Harriet out of the pink van, but the lady was not for three-point turning.

The deputy leader averred that it was important that the 9.1million women who did not turn out to vote in the 2010 election had their voices heard at long last. By other women looking like they are trying to sell them insurance from Sheila’s Wheels.

So now Ms Harman, accompanied by fellow female MPs Gloria De Piero and Lucy Powell will go from town to town taking their “battlebus” to the fairer half of the British people.

What will female voters make of it? I imagine that, after they’ve picked themselves off the floor and stopped laughing, they’ll think precisely the same as male voters: “Why has someone parked a van advertising women’s sex toys on my high street?”

Of course Harriet is quite right that there’s absolutely nothing patronising about throwing a bunch of women into the back of a pink van and driving them round the country to talk to other women. It’s not as if she put glitter or fairies or unicorns on the side of the van, is it? She’s a serious politician, after all.

As she insisted just two months ago: “This is a watershed election for the prospects for women. It is going to determine whether women go forward with their lives or all the progress is stalled and we go back.”

Going forward may be the least of their problems. First they’ll have to master the perils of parallel parking