An eight-year-old boy who disappeared off the streets of London after watching the Royal wedding procession of Prince Charles and Lady Diana Spencer, may have been murdered by one of Britain's most notorious paedophiles.

A new documentary, In the Footsteps of Killers, has uncovered connections between schoolboy Vishal Mehrotra and fairground worker Sidney Cooke, who led a gang which became known as the 'Dirty Dozen'.

Silent Witness star Emilia Fox and criminologist Professor David Wilson have discovered a diary placing Cooke in Goodwood, West Sussex, on July 29, 1981, the day that Vishal went missing.  

The diary had been seized by police from Cooke's housemate Dennis Moran, who has since died.

'That could be potentially very significant,' said Wilson.

Vishal's partial remains were found in Alder Copse, near the village of Rogate, which is 13 miles from Goodwood. 

'We also know that he knew this area because he had encyclopaedic knowledge about fairs and fairgrounds and we know that there was a campsite that fairground workers would use here and there's every chance he was aware of Alder Copse,' Wilson added.

It is now 34 years since Cooke, who also went by the name 'Hissing Sid', and members of his gang, were jailed for the manslaughter of 14-year-old Jason Swift.

The 95-year-old has since received two life sentences for a series of sex offences which occurred between 1972 and 1981 and is still in jail having been refused parole on ten occasions.

He and fellow paedophiles Leslie Bailey, Robert Oliver, and Steven Barrell, drugged and raped Jason at a flat on the Kingsmead Housing Estate in Hackney, east London, in 1985, before dumping his body in a copse in Essex.

Bailey, nicknamed Catweazle, was later convicted of the manslaughter of Mark Tildesley, seven, whom he raped in Cooke's caravan in 1984 while visiting a fairground near Wokingham, Berkshire.

Bailey, who was murdered in his prison cell in 1993, was also convicted of the murder of Barry Lewis, six, Slot Bonus who was abducted in 1991 and sexually abused by up to eight men.

His body was found in a shallow grave near Waltham Abbey, Essex.

'It strikes me that none of the boys - Jason, Barry or Vishal - had been buried,' said Wilson.

'Their killer or killers hadn't brought to the deposition site spades or shovels and dug a grave for them, but their bodies were left on top of the land, out in the open because the area is so remote.'

The programme also tracked down Paige Exelby, the granddaughter of a woman, who believed she had seen Vishal on the tube with Bailey on the day of the Royal wedding.

'My Nan was visiting my Mom in hospital, in St Thomas' Hospital in Tooting,' she recalled.

'She had to get three trains to visit my mom and she would do that every single day.

'On her way back from visiting my mom, she got on, I believe it was the District Line, and saw a young boy himself relatively, but sort of very excitably sat on the train.

'She described him as Asian, and her description was definitely that he was very keen on his trainers.

She described them as a White Flash. Also, on the train was a man that my nan described as 'Catweasel'.

'My nan described them as if they weren't together, he was definitely taking note of the boy. Whether or not the boy knew about him, is a whole other question.

'The next day when she saw a picture of the boy that she had seen on the train in the papers, Vishal Mehrotra, she called the police.

They said: "Yeah, we'll send somebody out" and nobody came.

'A few years later - it could have been months -she was reading the newspaper and she came across an article about a paedophile ring, a paedophile gang called The Dirty Dozen.

And one of the pictures she said: 'This is cat weasel.

This I the man I saw with Vishal,' and that was him, Leslie Bailey.'

Wilson now hopes his cold case investigation will bring some closure for Vishal's father Vishambar.

'I hope we've done enough to demonstrate to the Sussex Police that they should regard Sidney Cooke as a prime suspect,' he added, 'and to interview him again before it's too late for Vishambar and his family to get justice.'

In the Footsteps of Killers: The Murder of Vishal Mehrotra will be available to watch on Channel 4 from January 12.