I am sitting with an abortionist in a counselling room in a central London clinic. Downstairs, on a padded surgical bed covered with blue paper, 5,000 pregnancies a year are ended. In the waiting room sit women and their male lovers. None of them is leafing through the magazines provided, but some are clutching Kleenex.

All look haunted. Don’t panic. This isn’t going to be a Me and My Abortion article, a grim Tracey Eminish journey through my harrowing gynaecological history.

I’m here because it’s the 35th anniversary of Roe v Wade in the US, a country where a woman’s right to choose is far from constitutional and remains under constant attack from the pro-life, evangelical Christian Bible Belt and the Catholic church; a country where schoolchildren are encouraged to adopt, name and pray for the souls of blastocytes destined for termination, and where a bill signed by Governor Mike Rounds, in South Dakota almost two years ago, made abortion illegal in most cases, including rape or incest.

I’m here because the pro-life lobby is also making hay in Britain. Antiabortion lobby groups are attempting to hijack the Human Fertilisation and Embryology Bill currently going through the Lords, in the hope of introducing an amendment that would chop the time limit on legal abortion from the current 24 weeks down to 20 weeks. To commemorate the 40th anniversary of the Abortion Act last year, there was a rally in Westminster and a ghoulish “service of remembrance” for the estimated 6.7m foetuses destroyed since 1967.

There are also upsetting stories around that women are airily opting to abort for abnormalities as minor as cleft palates, webbed toes and club feet, stories that do not stand up on examination, but are designed to add to the impression that our abortion rate is immorally high; that women are treating abortion, even at advanced stages of pregnancy, as a form of contraception; and that women are choosing to kill their own babies because of some minor, indeed cosmetic, defect.

But I am here, above all, because there has been a war of attrition between the pro-life and the pro-choice campaigns on both sides of the Atlantic for decades, and if I am going to discover what is really going on, I need to report from the front line of this war – the abortion clinic.

So here goes, taking each of those three charges in turn.

Yes, the abortion rate here is high (though curiously it’s even higher in the US). But the fastest rising rate of abortion is for under18s. Deanna, who manages the Marie Stopes clinic I am in, says: “Business is growing all the time, really, because of binge drinking and teenage pregnancy, coupled with the fact that lots of girls are simply clueless about contraception.” So it would seem that the protesters should not be tough on abortion, but the causes of abortion.

Two, women choose abortion as a form of contraception. Frankly, I don’t know anyone who would choose foeticide as their preferred form of birth control. I do know lots of women, however, who have taken responsibility for not bringing another baby into the world when the resources – emotional, psychological and physical – sadly aren’t there for it.

And as for late-term abortions, there is no evidence that these are being sought for trifles such as webbed toes alone. There were 136 terminations beyond 24 weeks in 2006. All of them were for what is called a “ground E” case – meaning if the child was born, it would be seriously handicapped.

Meanwhile, about 1,100 women had an abortion between 22 and 24 weeks: teenagers who panicked and hid their pregnancy; women who had no idea they were pregnant because they were on the contraceptive pill. One wonders what on earth these girls and women would have done if safe, legal procedures weren’t available for them.

“I didn’t go through uni and med school thinking, ‘Yes! I want to be an abortionist’,” says Dr Kate Worsley of Marie Stopes International, who has carried out many. “But it’s a small aspect of medicine that’s most needed to be done well.” According to the World Health Organisation, unsafe abortions kill more than 66,000 women worldwide every year. The Lancet has called it one of the most neglected public health issues of our time.

British women are lucky. The law gives us strength and legitimacy to decide what is best for us and our families, and control over our reproductive destinies. Any changes to return that power to MPs or lords (few of whom will face the experience of abortion themselves) will erode trust in women to take responsible decisions about their own pregnancies. As the American feminist Florynce Kennedy said: “If men could get pregnant, abortion would be a sacrament.”

I came away from the clinic with nothing but respect for the doctors – trained, after all, not to take away life but preserve it – sympathy for their patients and more than ever convinced that the decision to end a pregnancy, whether wanted or unwanted, is never undertaken lightly by the woman who needs the termination or the doctor who performs it.

“Every day, women leave the procedure room,” says Worsley, “and they always turn and say, ‘Thank you’.”

I understand why.

It took years for the greens’ miserabilist message of doom and gloom to be adopted by the mainstream media who now, as if to make up for lost time, send reporters to deliver pieces to camera from beneath Antarctic glaciers or halfway up a gumtree in the Costa Rican rainforest at the drop of a hat. You can hardly switch on the news without seeing a telly chap swinging from a helicopter or harness, complete with hard hat and large wedgie.

But now the greens are worried they have overplayed their hand, and so their new message is: chin up, we can all save the planet, it’s never too late to start composting. I saw them all at the launch of Andrew Simms and Joe Smith’s ace new book, Do Good Lives Have to Cost the Earth?, in Fitzrovia (everyone wore green, arrived on bicycles and grazed on canapés of authentic English cheeses as a quartet played lutes. Honest).

None of the starry contributors appeared to be there (all on their organic farms, book tours or at Davos) but anyway, I asked Andrew Simms when he thought that the greens finally started preaching to the choir.

“Well, I thought that the piece Susie Watt did for Newsnight last week, questioning whether economic growth is good, was a real marker,” he said, “But I think the real conversion took place about 18 months ago . . .” He trailed off to snaffle a tranche of Cornish yarg before resuming, “when I was asked to attend a BBC seminar on climate change, and Fergal Keane was there.”

We both nodded. For the BBC, of course, only rolls out the Fergal when it thinks something really awful that will make us cry is going down.

rachel.johnson@sunday-times.co.uk

Times Recommends

• Fragility always gets my sympathy vote
• Double it and you get the real jobless total
• Has al-Megrahi paid his council tax?