New graffiti evidence released in fresh bid to solve Sean McGann murder 40 years on

'Very sorry' and 'no I'm not' were found written on a wall by detectives reviewing old crime scene photographs from the attack in April 1979.

On BBC Crimewatch on Thursday (September 26), Detective Chief Inspector Joe Banfield hoped this would lead to a breakthrough in the case.

"This could be really, really relevant - it might not be - but what we know is that it hasn't been released before and we'd like to know is if anyone knows who wrote that or if anyone knows anything about it," he said.

Sean left his grandparents' home in Victoria Gardens sometime between 5.30pm and 6pm on April 17, 1979, to visit the funfair at Midsummer Meadow.

He was supposed to be home by 7pm but never showed up - his body was found in an alley near Birchfield Road East at around 8am the following morning.

Police believe the 'lovely' boy was strangled in a potentially sexually-motivated killing somewhere else but his body was in the alleyway for less than an hour.

DCI Banfield said his belt and shoes were found nearby but his glasses and jacket were never discovered, suggesting he could have been in a house overnight.

The officer also appealed for anyone with information about an anonymous letter sent to Sean's family in 1991 to come forward.