At home, Abid Saddique and Mohammed Liaqat, both of whom were married with young children, were considered clean, upstanding family men as well as devout Muslims.

But once they left their front door and their wives behind, they turned into vodka-swilling, cocaine-binging paedophiles who spent every available moment randomly targeting young girls on the street, befriending them, and then horrifically abusing them.

The 28-year-olds were at the head of a 13-strong gang who would film the assaults on their mobile telephones.

For over 18 months, dressed “sharply” in designer western clothes, wearing jewellery and sporting short haircuts, the pair cruised the streets of Derby in a silver BMW 5 series with blacked-out windows, approaching girls at random and with a bottle of vodka and plastic cups hidden under the front seats.

An undercover investigation by Derbyshire Police, dubbed Operation Retriever, was split into three trials which have run since February at Leicester Crown Court and can only now be reported.

The victims, aged between 12-18, ranged from girls in care to a 14-year-old A-grade student from a strong, middle-class home. They were predominantly girls with a troubled background.

They would pick their victims up night and day and from anywhere - at train stations, on estates, in the city centre, walking home from school.

They would be charmed, given drink and drugs, and after mobile numbers were handed over, contacted again to meet up, go to a party or for a drive, where the abuse took place.

At the opening of the first trial, held at Nottingham Crown Court, prosecutor Yvonne Coen QC said: "They preyed on young girls who were vulnerable, either because of their age and because of their own personal circumstances.

"They exploited these girls either for their own sexual satisfaction or for their friends.

"The girls involved in the case were young and however cool and grown-up they may have wanted to be or intended to appear, in fact they were naive and impressionable.

"The reason for the main defendants' relentless pursuit of the girls in this way was quite simple. They wanted sex, whether the girls wanted sex or not."

In one incident, Saddique, who was convicted of 14 of the 29 charges he faced, was accused of engaging in sexual activity with a 12-year-old in Derby’s picturesque Darley Park, while his accomplice Liaqat, who was convicted of 10 crimes of the 18 charges he faced, had sex with a 14-year-old in the BMW.

Another time, a 14-year-old girl was filmed having sex with three of the gang in a hotel room as cheers ring out.

The group faced 75 charges between them relating to twenty six girls, but police believe there are many more victims who have not come forward.

Yesterday, Saddique and Liaqat - who since legal proceedings have begun had grown long beards and now wear Islamic dress - were convicted of charges of sexual assault and sexual activity with a child, bringing the trials to a close.

This year they had already been convicted of a series of other offences including rape, sexual assault, sexual activity with a child, false imprisonment and making child pornography. They will be sentenced for all their crimes in January.

Police believe the organised campaign would have carried on a lot longer had it not been for a chance arrest on December 30th 2008.

Derbyshire police had already heard rumours of a paedophile gang operating in the city when Staffordshire police stopped a car in Burton-upon-Trent, carrying three men – including Saddique and Liaqat - and two girls, on suspicion of shoplifting.

The girls were driven back to Derby, and tipped officers off about what was going on.