The glass ceiling seems closer to being shattered

If Mrs Clinton gets her way she'll be celebrating her 70th birthday in the Oval Office as the newly sworn-in first female leader of the free world. The only thing standing between her and that date with destiny is the challenge to persuade the majority of American voters that she is the candidate for the job.

With 51 per cent of the US population female, she should stand a fair chance. She must be hoping that, when faced with such an historic opportunity, the women of America will put gender before party.

The question is: should they? Should women vote for women as a matter of principle until the age-old discrimination that has held down half the human race has been properly overturned?

In this country and at present it can feel that we enjoy full equality of education and opportunity. But the playing field isn't as level as it might seem. How could it be after such a history of discrimination?

Here are a few random facts: Women in this country still don't enjoy equal pay. In the 21st century the Church of England has just appointed its first woman bishop.

There were more male MPs in the House of Commons this year than the total number of women MPs in history. No wonder the UN Committee on the Elimination of Discrimination against Women concluded in 2012 that the most critical issue for women's equality was political representation.

Yet what we saw writ large in the televised UK leaders' debate was the ability of the women who took part. Natalie Bennett, leader of the Greens, and Leanne Wood, leader of Plaid Cymru, were equal to the more practised Ed Miliband, Nick Clegg and David Cameron. By many accounts, Nicola Sturgeon, Scotland's first female First Minister, surpassed them.

This demonstrated to anyone who still needed to be convinced that there is nothing in the intellectual make-up of women to prevent us from exercising power.

Across the world, 22 countries have women leaders (out of around 250). Angela Merkel, the iron lady of Germany, is the most powerful. Women are also in power in countries as diverse as Norway, Argentina, Bangladesh, Trinidad, Denmark and Chile; and, of course, here in Scotland.

Though it is only one tenth of the world it is progress. But, oh Lord, it's such slow progress, even in the liberal and enlightened West. And it's not just politics where women struggle to be represented in equal numbers. Take business, for example.

A new government report shows that the percentage of women on the boards of FTSE 100 companies will soon reach the 2015 target of 25 per cent. In the past two years, one third of board appointments have been women.

It is inching in the right direction but what happens when the target is reached. I presumed, as most women might, that it would then carry on to the 51 per cent reflected in the population. Dr Elena Doldor, a co-author of the report, is less optimistic. She expects female representation to stagnate at around 28 per cent. She said: "There are still not enough women on executive committees or in the executive pipeline. Introducing aspirational and measurable targets for women at all levels is the only way to achieve real progress."

Another recent report from America found something disturbing. It was that a woman's chances of landing one of a company's five highest-paid executive jobs drops 51 per cent if there's already a woman in the senior team.

Although the explanation is not entirely clear, unconscious male bias could be at work. "It might very well be the case that male top managers just want to check a box. There is no more effort, no more mentoring, to appoint a second woman to the top management team," said Cristian Dezso, an associate professor at the University of Maryland's business school and an author of the study. "They are one and done."

This situation exists despite analysis of thousands of audit reports demonstrating that gender balance outperforms all male or all female teams.

But if women believe in parity and want to see it established in time for their daughters to enjoy real equality of opportunity, should they vote tactically at all times? Should they look more to the gender of their candidate of choice than to her party?

After all, the rich tend to support a party that protects their wealth. Trades unionists prop up the party that will look after their members' pay. Across the UK, there are five million workers earning less than a living wage. Most of them are women. So why shouldn't women vote on grounds of gender, in the hope that their own kind will legislate to their benefit?

A female leader is not in itself enough to deliver real change for women. Mrs Thatcher was proof of that.

Indira Gandhi was India's fourth prime minister. Her daughter-in-law, Sonia, has been president of the Indian National Congress since 1998. Yet no one who watched the recent documentary about the young woman doctor who was raped and murdered on a bus because she was out with a male friend at 8pm could imagine that women in India have equal status. Even the rapists' lawyers - educated men - said she was to blame.

Nor can we be complacent. In Scotland, where most women don't think twice about our equality, the conviction rates for crimes such as rape and domestic violence remain amongst the lowest in Europe. In Britain, female genital mutilation goes unprosecuted. There is plenty of room for improvement.

So I ask again: should women simply vote for women? If only it were so simple. It would mean backing Marine le Pen in France. It could have catapulted Sarah Palin into power in America. Sadly, female candidates can be equally bad and equally venal, as well as equally able.

However, where a female candidate is reasonable, surely gender should tip the balance?

Mrs Clinton is such a candidate. Certainly, she is flawed. As a former First Lady and Secretary of State, she is also experienced and savvy. When she lost the Democrat Party nomination to Barack Obama, she was gracious in defeat and generous in offering his administration her talents.

She said then to her supporters: "Although we weren't able to shatter that highest, hardest glass ceiling this time, thanks to you it's got about 18 million cracks in it and the light is shining through like never before, filling us all with the hope and sure knowledge that the path will be a little easier next time."

If she can break through this time her election will bring to women the world over the same sort of fillip that Mr Obama's election brought to people of colour. I'm not saying it would be the answer, that it would right all of the wrongs. But it would point the way for women everywhere because it would demonstrate louder than words that anything men can do women can do just as well, Ginger Rogers style, backwards and in high heels.