Andrew, who is now aged 15, was last seen on CCTV footage coming through Kings Cross station on 14 September 2007. He travelled by train from Doncaster to London but has not been seen since.

Supported by the Missing People charity, Andrew's family has organised a multi-faith service, which will be held at St James's Church, in Piccadilly, on Sunday at 3.30pm.

The service will publicise the disappearance of Andrew and other missing children.

Andrew's family are bringing a team of about 100 volunteers to distribute thousands of the charity's posters of Andrew across the capital.

Missing People has organised posters, an appeal on its website, and publicised Andrew in its appeal slots on plasma screens on buses and in doctor's surgeries.

Andrew's mother Glenys said: "It will be a difficult day, but is probably the nearest thing we can get to closure over this. It is our way of saying we've done all we can.

"London is the worst place he could have gone in terms of trying to find him."

Missing People's director of services, Ruth Mulryne, said: "We desperately hope that this service and the publicity that it generates will finally find Andrew and put an end to his family's suffering."

For more information about the charity, visit www.missingpeople.org.uk.