A teenage girl dials 999. Her young sister has been watching from the window as their mother is dragged into the garden by her partner and brutally assaulted. It is not the first time the sisters have called police. In fact, the girls have reported most of the 14 other attacks known to police.

This family is not alone. They are among hundreds of victims of domestic violence reported to Greater Manchester Police each week and among ten high risk cases being discussed in Bury as I sit in on a conference dedicated to protecting victims.

The dozen or so representatives on this multi-agency risk assessment panel – police, social services, education, health, youth offending and alcohol workers – meet fortnightly to take action on those most at risk.

A mother who has turned to drink after her ex slashed her throat with a bottle. A woman who has been punched in the head because her children woke their father up and another who has been raped and beaten, almost suffocated and now attacked in the street. The latest incident was reported by her neighbour but the victim has never given a statement. She is too afraid.

Another woman up for discussion was so terrified to speak to police that she could only write down the address her ex had fled to. Other victims deny any knowledge of the 999 call when officers knock on their door. These women are the victims of control freaks.

“I think it’s part of women’s psyche that they blame themselves,” explains Detective Inspector Jane Little, head of GMP’s Public Protection Investigation Unit in Bury. “They feel a responsibility to keep the family together. Unless that woman is telling us everything that’s going on, we don’t know everything. We are between a rock and a hard place. There’s a danger that if we intervene when a woman doesn’t want to give evidence, she won’t report the abuse again.

“Each incident is a risk assessment. Every case has the potential to be a homicide.”

Eighty-nine per cent of known victims are female and one-third of domestic abuse starts in pregnancy. Police install protection measures in homes everyday, from alarms or safe rooms to cameras, extra lighting or reinforced windows.

“In certain cases, perhaps opportunities have been missed,” DI Little says. We are talking about Katie Boardman, the young mother from Bolton who was stabbed to death by her ex-boyfriend. GMP were slammed for their ‘total failure’ to link 11 pleas for help.

“We know we can do better. What we’ve realised is that officers on the front line haven’t been as well trained as they could at spotting the signs when they’re called to an incident. We are rolling out that training.

“We have a duty to protect that woman and the next woman a perpetrator goes to. When a woman doesn’t want to go to court sometimes we have to summons them. Then it’s not their decision. That can be better for them – we’ve made them do it. But no case is black and white. It’s very grey.”

Back at the Public Protection Investigation Unit, a discreet terrace property known only to those who need it. A team of 20, mostly female staff – 17 police and three civilian – deal with a host of domestic incidents.

They include checks on an address where a one-time victim has gone missing, calls to the mother of a 16-year-old who fled after her boyfriend threatened her with a knife and supporting a woman in court for lashing out following months of abuse.

Bury may be one of the force’s smallest divisions but it deals with up to 100 domestic incidents a week. Around half involve children. The unit handles 4,500 incidents a year – one in five result in criminal investigation. It is said to take seven years of abuse, or 35 incidents, before a victim reports it.

“We get lots of calls from mums, lots from neighbours, but there’s nothing we can do until the victim is ready,” one of the officers tells me. “People come to our door two or three times before they ring the bell. Sometimes they call 999 because they are just so frightened and they know when we get there it stops. But that doesn’t mean they’ll talk to us when we call them later.”

“Some of these guys are real nasty pieces of work,” says DI Little at the multi-agency risk assessment panel. “They are involved in other crime, drugs, organised violence. If you can’t get them on domestic violence you try from any other angle.”

She is talking about a man who has abused his last two partners. He shaved his ex girlfriend’s head and has threatened to kill his current partner. Specialist workers will visit her again but she does not want to leave her home and will not support a prosecution. She hopes it will ‘blow over’.

“You can protect people to a certain point,” says DI Little, “but you can’t do what you don’t know about. That’s why above all it’s really important that victims report every incident.”