Rachel Connor, 26, was determined to bring the culprits to justice after the attack outside an Otley pub.

Rachel, sister Kelsey, 18, and her boyfriend John Bristow, 23, were all viciously assaulted by a group of men and women one night in April 2008.

John had his jaw broken in four places – and still needs a metal plate – while Kelsey and Rachel were left cut and bruised.

Although police investigated the attack, Rachel went one step further and set up her own Facebook group called 'Fight Outside Rose And Crown Pub - Were You There?' The page including descriptions of the attackers and Rachel sent the link out to friends.

Within hours people were posting messages saying they'd seen the attack while others sent private messages giving names.

At one stage there were 800 people in the group. West Yorkshire Police told Rachel that a woman had been cautioned and received an £80 fine for a public-order offence.

Rachel said: "I'm convinced that my Facebook group played a part."

Rachel was living in Otley with dad Paul, 50, when Kelsey and John came to stay for a week from their home in Liverpool.

They all got talking to a group of men and women aged between 18 and 24 in the pub before violence erupted.

"They started calling John a scouse b******. These lads then followed us outside and shouted abuse at John. By the time I came out of the pub Kelsey had this girl on top of her ragging her head about, John was on the floor holding his face, screaming.

"Someone had hit him in the cheek with a knuckle duster and broke his jaw in four places."

Rachel tried to break up the fighting but was grabbed from behind by one man who shoved her head on the pavement.

They were stopped after dad Paul pulled them all apart and the gang fled.

Rachel added: "I was so angry. I did not want vigilante justice but I thought everyone is on Facebook so it might help find them."

Kelsey has since moved to Leeds and lives with her dad in Shadwell.

A West Yorkshire Police spokesman said the force had appealed to the public for information about the attack on May 12 2008. He added: "The appeal was also present on our website, to which thousands of people subscribe to receive news updates. (The force] now also has a dedicated Facebook page, on which all of our appeals are posted."

* This story appears in the November issue of Cosmopolitan.