Anita O'Connell, 28, is now a respected worker with a mental health charity in Greenwich. But between the ages of 13 and 18 she was involved in violent offences and ended up serving seven months in Holloway prison. She still lives on the Thamesmead estate in South London where 15 years ago she hung around with gangs of girls.
"From a very early age I was bullied by a gang of about ten girls from a caravan site near the estate," she says. "Every time my mum sent me to the shops I was a natural target. They'd be lying in wait and they'd set on me and there'd be slaps round the face and scratches. I soon learned to fight back, but it was mainly defensive fighting and kicking if someone picked on me and my friends.
"By the time I was 14, I was hanging round with a gang of girls myself. Five or six of us would bunk off school, go away from the estate and sniff Tipp-Ex thinner and butane gas and drink lager and cider. There was nothing to do on the estate and the worst thing we did to other people was playing Knock Down Ginger - a stupid game where you'd ring people's doorbells then run away. I guess people thought of us as a girl gang and maybe people found us intimidating but we didn't do anything violent to anyone and we certainly didn't carry any weapons.
"My first conviction was for thieving car stereos to get money to buy the butane which cost pounds 1.20 a can - between the ages of 14 and 17 I was getting through six cans a day. I did the cars with a younger boy, not with the girls - they were too prissy to go thieving.
"I don't honestly think that 15 years on things have changed all that much in Thamesmead, though I do think girls are louder and more assertive now. I see 15-year-old girls going round the estate in bigger groups, and they drink alcopops like Hooch.
"They dress more grown-up than we used to so they have no trouble buying drink and yes, they're very loud and they do shout abuse. I think people living on the estate find them intimidating because adults equate offensive language with physical violence. But just because women have become more assertive verbally, it doesn't mean they're more physically abusive."
It is certainly true that women are no longer satisfied with a passive, subservient role, and social change has made it acceptable for girls to challenge men in every arena. Role models such as the Spice Girls and Lara Croft encourage girls to be feisty. But it is important to resist the simplistic and inherently misogynistic equation that liberated women are more violent women.
Anita's observation about the increased availability of alcohol is more pertinent. Thirty years ago alcopops did not exist, supermarkets did not stock liquor alongside the groceries, and it was unusual to see women, let alone teenage girls, on their own in pubs or out on the streets late at night. But now few young women would think twice about walking into a bar or club and ordering a drink. Earlier this year 19-year-old Lianne Thomas was sent to Holloway after a nightclub row ended with her scarring another girl's face with a broken glass. This week's Home Office report Alcohol and Crime: Taking Stock revealed that alcohol plays a significant part in 75 per cent of all assaults, because alcohol is so often a trigger to aggression in women as well as men.
So is crack cocaine. The number of women in prison has doubled over the last five years and, according to figures released in June by Linda Jones, head of the Prison Service's women's policy unit, half that increase is due to drugs. One third are there for drugs offences such as possession and supplying, and another third for drug-related offences - burglary, often to fund a habit, has increased by 18 per cent. The Portsmouth muggings, like Anita's car thefts, were drug- and alcohol-related, as was the brutal murder of an elderly widow last year by two schoolgirls who dumped her body in a wheelie-bin.
But we must keep a sense of proportion. Dreadful as these offences are, the figures for girls convicted of violent crime are still minute in relation to the total prison population of 66,000. Although the number of teenage girls in the prison system has quadrupled since 1992, it is important to remember that in that year only 25 girls were given custodial sentences, rising to 60 in 1996 and 90 in 1998. The base figures which promote so much media hype are often equally slim. Last July a study of teenage female violence produced shock headlines: 80 per cent of girls had been involved in fights, and by the year 2008, girls would be committing more violent acts than teenage boys. The study was based on interviews with just 40 female teenage college students in the Midlands. More reliable is the British Crime Survey, in which 96 per cent of mugging victims said they were attacked by all-male gangs, two per cent by mixed-sex gangs and two per cent by all-female gangs.
Chris Tchaikovsky, of the charity Women in Prison, is wearily familiar with the prurient fascination with the idea of the female of the species being deadlier than the male - a fascination which keeps Myra Hindley on the front pages. And if the violent females are pubescent Lolitas, it makes them all the more exciting.
"A few years ago there was a great deal of media hype about a 10 per cent increase in the number of girls aged between 15 and 18 sent to prison for wounding," says Ms Tchaikovsky. "As there were only 36 girls of that age in the entire prison system, the rise represented just three and a half girls!
"Yes, incidents like the one this week are dreadful, but we need to remember that they are reported just because they are so rare. I call it the Woman Bites Dog Syndrome."
But Ms Tchaikovsky is worried that such persistent media mythology may turn out to be a self-fulfilling prophecy. "The girl gang/Tank Girl myth is an idea we have imported from the USA. But the British media, too, are guilty of creating history rather than recording it. We all remember that fight on a Clacton beach between two groups of youths whom the media christened Mods and Rockers. After that, the battles went on for years."
The Howard League for Penal Reform believes this is already happening. In its 1997 report Lost Inside: Teenage Girls in the Criminal Justice System, the League blamed the rise in female youth convictions on the media coverage of the mugging of Elizabeth Hurley by three teenage girls. They were portrayed by the tabloid press and in a Panorama programme as monstrous predators, but workers from Women in Prison who supported them in Holloway can provide a much more complex picture. Two of the girls were homeless, and all were penniless and hungry on the London streets hundreds of miles from their homes. The "gang leader" said they approached Ms Hurley thinking she was "a high-class hooker who might give us money for a burger". This girl pleaded guilty to pulling out a small knife that she carried for protection and said she was full of remorse about the whole incident.
Lord Hurd, in his role as chairman of the Prison Reform Trust, has expressed the view, widely accepted in penal reform circles, that the sentencing policy of the courts in relation to young boys hardened as a direct result of the murder of Jamie Bulger - still, as we saw last week, an open wound in our national psyche. We must make sure that cases like this week's attack, terrible as it was, do not have the same effect on teenage girls who break the law.