Since then detectives have carried out extensive enquiries, appealing for any witnesses or anyone with information about the terrible crime to come forward.

And with Friday November 7 marking the 20th anniversary of her disappearance, officers are appealing once again to the local community for help to crack the case.

Detective Superintendent Simon Atkinson of the Protective Services (crime) department has issued a video appeal:

He said, "Someone, somewhere knows what happened to Lindsay and I am appealing directly to that person to come forward and help me bring closure to Lindsay's grieving family.

"For 20 years Lindsay's family have had to live with the pain and the hurt of not knowing what happened to her as her killer continues to enjoy his or her liberty.

"Every time they pass someone in the street they might be thinking – 'was it him' or 'was it her'. The pain of losing a loved one in this way has caused them immeasurable suffering and not knowing who did this makes it even worse.

"Lindsay was a young girl with her whole life ahead of her and no-one knows what she could have become – her killer or killers took that away from her.

"Over the years loyalties change. You may have had suspicions about a friend or a loved one back in 1994 but never came forward out a misguided sense of loyalty. I am appealing directly to you to come forward.

"The information may seem trivial to you but could be the final piece in the jigsaw needed to catch a killer."

For the first time ever the police are using a 'tweeconstruction' to help spread the message. A 'tweeconstruction' is a reconstruction of the case and appeal using the social media platform, Twitter. It will start at 11.15am on Friday 7 November. Follow their Twitter feed here.

On November 7 Lindsay left her home on Cambridge Street, Hebden Bridge to go to the shops. She paused briefly at the Trades Club on Holme Street where she met her mum before buying the cornflakes.

Anyone with information about the crime is asked to call detectives directly on 01924 334604 or text on 07786 200805. Alternatively contact Crimestoppers in confidence on 0800 555 111.