I dreaded the sound of the doorbell when I lived in a Manchester block next door to sex workers. But no one in authority did anything

What can you do when a 12-year-old girl is being abused next door?

Throughout the 1990s, I lived in an apartment block in Manchester where conditions might accurately be described as challenging, complete with drug dealers and tenants who lived what are euphemistically termed "chaotic lives". It was near the red-light area and sex-workers operated in the car park or illicitly sublet flats.

This was true of my neighbours. Hearing unbearably loud music one afternoon, I visited to request they turn it down. The door was opened by a girl I later discovered was aged just 12, though she was old beyond her years with deep shadows under her eyes. She was aggressively defensive, telling me that even if I called the police they wouldn't do anything. She could do whatever she wanted "so fuck you". Then an older girl (who I learned was 18) moved her aside. Maria was conciliatory, saying they didn't want trouble.

Of Asian heritage, Maria was rake-thin and haggard. I often saw them both in the foyer with different men, including neighbours. My doorbell rang throughout the night, pressed in error by men who asked for Maria or "that nice little black girl". I told them forcefully to leave, but many were undeterred.

I have been an advice worker, and am aware of the futility of this situation: a worldly wise, older sex-worker guiding a runaway young person.

But I dreaded the sound of that doorbell. I knew what it meant: child abuse next door. Whenever abusers rang by mistake, I took to racing downstairs to confront them. I told those creeps that, if they were stupid enough to park outside, I had noted their car's registration, asking them to smile because they were on CCTV (more in hope than belief).

Alternatively, I would shout: "I bet you've got a daughter her age!" Judging by their guilty expressions, many did. A minority had enough humanity to look ashamed, while others sidled off. At least I prevented some abuse.

One day I bumped into Maria in a local shop. Proudly, she showed me some frozen ready-meals: "I try my best," she said. "At least we're eating properly."

As we walked home, I said: "Maria, please stop working. I will help you." Quietly, she replied: "I can't."

At Christmas they acquired a vicious weapon-dog that howled forlornly whenever they were out. When it vanished, Maria explained her pimp had "taxed her for it" – stolen it.

In desperation I asked the community police officer to visit and, as requested, described the girls: "One mixed-race 12-year-old and an older Asian woman."

"Oh," he replied, pointedly. "Coloured persons." I told him "coloured" was not a term I would use.

"I expect they're dirty and wearing scruffy clothes?" he continued. No. They were well dressed.

"That must be very annoying for you madam: people like that wearing better clothes than you."

I reminded him that one girl was just 12 and begged him to investigate: check their names, discover where they were from, ideally help them to return home, and arrest their abusers. This beat copper wasn't taking notes, but reluctantly agreed to see what he could do. I wasn't confident he would.

While watching television one Friday night I heard a commotion next door: screaming in the corridor and doors slamming, nothing unusual until I saw a girl balancing out on my window ledge. I lived on the fourth floor, and beckoned her frantically inside, but she edged away. There had been a raid. My neighbours disappeared, along with the girl on the ledge.

A middle-aged woman had entered their flat, the mother of one of the many girls to stay there, some of whom I'd never seen. She said she had driven from Rochdale to rescue her 14-year-old daughter, speaking of abuse/sex-work in terms that rankled then, but in the current climate, resonate: "These Pakis pick her up from school and she disappears for months on end."

In the past, her daughter had been found in towns all over the north of England, including Rotherham. "I don't know why she does it." She said despairingly. "We give her everything. She's even got a telly in her room."

I was shown a letter received by her daughter while in care. It was the sleaziest, most disturbing thing I had ever seen. From one of her many abusers, it was sent in a package containing soap and razors, given: "So she could keep herself nice and clean down there" when next they met.

Nobody would help her mother, no matter who she asked. Inconsolable, she blamed "them Pakis" before driving home, shattered, helpless and hopeless, and without her daughter.

I never saw the girls again, except once, when I read a newspaper article on prostitution. The accompanying photograph was of Maria.

Names have been changed.