It is carried out for a variety of cultural reasons. Such is the secrecy that surrounds the practice that even those aware that it occurs in large swathes of Africa and Asia will be shocked to learn that it is prevalent in Britain.
During a highly disturbing, four-month investigation, however, we uncovered evidence that thousands of British-African girls, in towns and cities throughout the country, have been forcibly "cut".
By conservative estimates, 66,000 women and girls living in Britain have been mutilated. This figure, accepted by the Metropolitan Police, came in a report by a volunteer organisation funded by the Department of Health and carried out with academics from the London School of Tropical Hygiene and the City University.
And thousands more girls are at imminent risk as families club together to fly professional "cutters" from Africa to Britain.
These women "elders" perform the crude operation for up to £40 a time, often on kitchen tables or floors, without anaesthetic, using filthy, blunt knives, razor blades or scalpels.
Many readers will be distressed by our report, but this practice is an abomination which has no place anywhere, let alone in a civilised society, and if it is to be expunged then this is a story that must be told.
Whatever the arguments, the fact is that genital mutilation is a reality, and the Metropolitan police is so concerned that it recently set up a special unit to investigate and prosecute the perpetrators. Heading the unit is Detective Inspector Carol Hamilton, herself a mother, who was horrified when she discovered what was happening to other people's daughters.
The Met team also educates regional police forces about FGM, and speaks to mosques, community groups and local authorities.
Usually their visits are well-received, but we found that at least one London council declined to publish material highlighting the suffering and danger the practice causes - for fear of offending ethnic African residents.
This kind of attitude incenses Detective Inspector Hamilton. "We are all becoming very culturally sensitive," she says. "People are a bit frightened of saying 'You can't do this here' because people shoot back with 'But it's our culture'.
"But it's not: this is just plain cruel. I won't be put off by the politically correct argument. We have to be seen to be strong on this. I don't care about human rights - I care about the rights of the child. Everything else has to go out of the window.
"We have one rule in child protection: the child is of paramount importance. I stick by that firmly."
Together with the Waris Dirie Foundation, an international campaign group formed by the Somali-born supermodel who suffered genital mutilation as a five-year-old child, the Met announced a £20,000 reward last July for information leading to the conviction of anyone who performs or abets cutting.
Under the 2003 Female Genital Mutilation Act, those involved could be jailed for 14 years. Yet the fact that no one has been prosecuted says much about the problems the police are facing.
"There are thousands of girls being cut in your country," says Waris Dirie spokesman Walter Hutschinger. "We are sure it's going on, and on a very big scale. Your law is one of the most comprehensive in the world, but it is useless if nobody will help to implement it.
Perhaps we should take a lead from France, whose methods of prevention have been strengthened following a landmark case in 1999, when a woman of West African origins was jailed for eight years for cutting 48 young children.
Now all French children of African background are closely scrutinised by social workers and doctors during infancy, and any abnormal behaviour or prolonged absence from school is immediately investigated.
It is also considered a duty of French doctors to examine any ethnic African girls they suspect have been mutilated and, waiving usual patient confidentiality rules, report their parents to the police if their suspicions are confirmed.
In this age of political correctness, no doubt, factions in Britain will argue that such interventionist activity is discriminatory and a breach of human rights. There will also be those who believe female genital mutilation to be an issue for the African community to resolve, arguing that our overstretched police and health professionals have more pressing matters to address.
Detective Inspector Hamilton was persuaded otherwise when she sat through a graphic video showing a cutter at work. With its haunting screams and bloodied instruments, this real-life horror film changed her life.
"These little girls shouldn't have to live in that other world," she says. "They go to school here. Their homes and friends are here. They are our little girls. They are British. What is happening to them is barbaric - and it must be stopped."
I give a hearty and strong AMEN to the concluding sentence of this article. This must be stopped now. The UK should follow France's example of prosecuting this barbaric practice. Last year French Presiden Sarkozy awarded Waris Dirie the "Chevalier de la Legion d'honneur."
This has nothing to do with political correctness, and it infuriates me that anyone can even say something like that. There is no need to put any religious or cultural language into any laws banning this practice. We can outlaw this barbarism using our own words and language. And rightly so.
Here is a video of Waris Dirie speaking out against this.