War heroes left off the official Roll of Honour have been recognised and will be remembered with a memorial at their resting site following a Croydon Guardian campaign.

First World War servicemen, who were admitted to Cane Hill asylum, Coulsdon either during or following the conflict, failed to be included on the military roll of honour on death, and after the site was demolished, their bodies were cremated and scattered at Mitcham Road Cemetery.

Following The Croydon Guardian's Forgotten Fallen Heroes campaign, launched in September 2009, work from South Norwood local historian Adrian Falks, and research from volunteer organisations In From the Cold and Great War Forum, the names of four men have been accepted onto the roll and will be commemorated with a memorial at the site.

More than 40 poverty-stricken soldiers suffering from psychiatric problems were admitted to Cane Hill during the First World War. Mr Falks managed to uncover records for 26 of these men.

Hospital records show many of the soldiers died within months. Until the Croydon Guardian uncovered the scandal, they had lain forgotten in an unmarked grave for more than 90 years.

Mr Falks, 65, said: "I am delighted. Just because these men didn't fall on the battlefield shouldn't diminish the importance of the role they played."

Sergeant Alfred Charles Cartwright, Sapper George John Lammie, Corporal George Charles Lawrence, Private Walter William Sutton will be added to the digital roll of honour, kept by the Commonwealth War Graves Commission (CWGC) this week.

A Church of England minister and former civil servant, Mr Falks is hoping a further 22 servicemen who died at Cane Hill will be added to the list.

Terry Denham, who co-founded In From the Cold in 2007, explained how names could be added to the Roll of Honour.

He said: "If a soldier dies in battle, of course they are added, but on the other hand if a veteran dies in an accident following conflict, they do not. The grey area is where servicemen either during conflict or otherwise die off illnesses, mental or physical that may have been caused by the war. That is what we have to prove, with documents such as death certificates and service papers, for their names to be added."

For First World War servicemen to qualify, they must have died before August 31, 1921, the official end of the war, to be included.

Peter Francis, a spokesman for CWGC, said: "Cases like this are a fairly new phenonmenon. We still have a lot of cases under review with Cane Hill but once this has been completed we plan to erect a memorial honouring the servicemen from Cane Hill at their resting place at Mitcham Road."