Almost 70 years after one of the second world war's most notorious atrocities, Ian Clarke reports on the story of a true Dereham hero and how his son is seeking to ensure his father's suffering is never forgotten.

Almost 70 years after one of the second world war's most notorious atrocities, Ian Clarke reports on the story of a true Dereham hero and how his son is seeking to ensure his father's suffering is never forgotten.

You have to look very hard to find it. People who have lived in Dereham for decades do not know it exists - and many will not even have heard of the hero from within their community.

A small plaque on the wall in a courtyard of a modestly sized housing development called William O'Callaghan Place reads: 'In memory of William O'Callaghan, a brave son of Dereham, survivor of the massacre of Le Paradis, France, May 1940, placed by comrades of the Norfolk and Norwich Dunkirk Veterans Association.'

This weekend a group of relatives and fellow ex-servicemen will gather under the plaque and remember the life of Private O'Callaghan, one of two unassuming soldiers who ended up playing a pivotal role in bringing about justice in the aftermath of a wartime atrocity.

And coming close to the 69th anniversary of the infamous massacre at Le Paradis, a little hamlet south of Dunkirk in the Pas-de-Calais, Pte O'Callaghan's son Dennis hopes the event will help raise the profile of the Royal Norfolk Regiment signaller.

It was on May 27, 1940 that his father was among just under 100 officers and men forced to surrender to German troops after taking part in a last-ditch stand to enable the Dunkirk evacuation to go ahead. They were disarmed and, on the orders of German company commander Fritz Knoechlein, marched into a field to be mown down by machine-gun fire, before being finished off with revolvers and bayonet thrusts.

By some miracle, William O'Callaghan and his comrade Pte Bert Pooley, though both wounded, escaped death. Pooley woke his colleague by pulling at his leg having realised he was still alive. O'Callaghan surveyed the scene and, under the cover of darkness, selflessly carried his more seriously wounded mate away from the scene to shelter in a barn complex several hundred yards away. Then and there both men vowed that if they should survive the ordeal they would bring those who perpetrated the atrocity to justice.

Almost 70 years on, everything about William O'Callaghan's extraordinary story seems to beggar belief, from his incredible escape from death to his subsequent ordeal as a prisoner (partly set out out in a 1940 diary that has been transcribed by his son) and his crucial role in helping bring about the conviction of Knoechlein at a war crimes trial in 1948.

So much so that it seems surprising that such a remarkable man has never been hailed a hero in his own home town.

Dennis O'Callaghan says of his father: 'I think there should be more recognition for him. It is something the town should not forget. Nor should we ever forget what they did to save us from the brutal oppression.'

His father never spoke about what he'd been through to his son and Dennis, who lives in King's Lynn, admits that he has found it painful and poignant to read his father's 1940 diary.

'It makes me very emotional and puts a lump in your throat that someone could go through that and play dumb and not tell anyone,' he says. 'I got so upset reading it. You have got to understand his state of mind and I think writing it kept him sane.'

The entries in his father's 1940 pocket diary begin in January, 1940, some five months before the Germans launched their blitzkrieg offensive on the western allies.

They are a mix of the humdrum and the harrowing, of mundane chores, weather updates and brief descriptions of action.

The following excerpts are typical:

New Year's Day: 'Went on duty at 6am came off at 2pm, slept for four hours on duty at 10pm, weather very cold.'

January 2: 'Aerial battle, German plane brought down, weather still very cold.'

Between January 28 and June 6 the pages are blank, as life became either too monotonous or too hectic. Certainly, after the Germans launched their offensive in May, there was precious little time for writing anything as the 2nd Royal Norfolks became embroiled in heavy fighting, first in Belgium and then during the retreat to Dunkirk.

By the time, William O'Callaghan resumed his diary he and his mate Bert Pooley were among the luckiest prisoners in captivity.

O'Callaghan spent the rest of the war - some five gruelling years - as a PoW in Poland before returning to Dereham. Back home, he gave a full account of what happened on that grim day in May, 1940, and later compiled a damning affidavit which is published here and which helped convict Knoechlein.

The search for justice, however, had already begun. For Bert Pooley, having undergone a number of operations on injuries sustained in the massacre, had been repatriated to England in April, 1943.

His initial reports of the atrocity were treated with scepticism. Even his friends thought the story 'too far-fetched' to believe. But at the end of the war, he returned to France and retraced his steps to Le Paradis, thus setting in motion the wheels of justice.

With O'Callaghan's return from captivity, his story was corroborated and both men were called as witnesses to the War Crimes Commission trial in 1948 which resulted in Knoechlein being convicted and sentenced to death for 'being concerned in the killing of about 90 prisoners of war of the 2nd Battalion of the Norfolk Regiment and other British units'.

William O'Callaghan, one time professional soldier, went on to work for a number of local firms, including Hobbies and Metamec. The only Norfolk-based survivor of the massacre at Le Paradis, he died in 1975.

Another decade passed before the local authority, under pressure from long-standing councillor Les Potter, who had grown up with O'Callaghan, agreed to name a small housing development after him.

And it is there, in William O'Callaghan Place, on Sunday, that his son will take part in a short ceremony of remembrance which he hopes will ensure his father's suffering and the sacrifice of his friends will never be forgotten.

The remembrance service will begin at 11am on Sunday at William O'Callaghan Place, just off Swaffham Road in Dereham. The service will include an assembly of standards, wreath laying and a brief address by Dennis O'Callaghan to be followed by the sounding of Last Post and a minute's silence.

Next year, to mark the 70th anniversary of the massacre, Dennis O'Callaghan will be leading a trip to Le Paradis that will focus on the Royal Norfolk Regiment connections. For more details call him on 01485 600742.