In the square outside the town hall of Newtownards in Northern Ireland stands a statue of an Ireland rugby player and one of the great military heroes of the Second World War.

It is of Robert Blair Mayne, universally known as Paddy, carrying in his right hand a book of poetry rather than a gun.

The low afternoon sun glints off the monument, which was erected in 1997 in memory of a complex man whose exploits as a sportsman and soldier were astounding and against whom his supporters, including veterans who served with him and are proud to be known as “Paddy’s Men”, believe a grave injustice was committed.

Mayne’s story is one of a remarkable individual. The lock forward, who toured with the 1938 Lions, was a founder member of the Special Air Service and one of the most decorated soldiers; a warrior, a rebel and a lawyer by qualification whose true vocation was war. He was awarded the DSO, the second highest medal for gallantry, four times and the Croix de Guerre. Official incompetence and prejudice, according to Mayne’s advocates, denied him the VC for which he had been recommended by among others Field Marshal Montgomery.

To his men and those who served alongside him he was simply “a legend”, whom they would follow without question, a man of volcanic temperament who was known to rail against the Establishment, who refused to stand on ceremony and was once on the verge of a court martial for striking a superior officer before being invited to join the SAS. He enjoyed poetry, singing and horticulture but also relished violence and confrontation.

It is a story, too, with a tragic but perhaps not unexpected end, of a man whose dark introspection and an inability to adjust to what he perceived was the humdrum civilian world in later life led to heavy drinking, mood swings and an untimely death at the age of 40 in a car accident.

But such is the impact he made in his lifetime and continues to make more than half a century after his death, that there have been campaigns to have his achievements properly recognised with the retrospective award of the VC. There were petitions to the Queen at the time of her Golden Jubilee and three early-day motions in the House of Commons. The last of these, in 2005, was signed by 105 MPs of all parties and stated: “This House recognises the grave injustice meted out to Lt Col Paddy Mayne.”

The Blair Mayne Association has been established to honour his memory and now has 7,000 members. After a debate last year the Northern Ireland Assembly backed the campaign with support from both the nationalist and loyalist sides. “It is our duty to spread the gospel,” Stewart McLean, one of the association’s founders, said.

Another motion is being considered, and it is hoped it will be sponsored by John McDonnell, the MP for Hayes and Harlington and the chairman of the Irish in Britain group.

Mayne was born in January 1915, one of seven children of a prosperous Protestant family. He excelled at rugby at school and also at Queen’s University Belfast, where he read law and became the Ireland universities’ heavyweight boxing champion.

A man of immense physical presence and courage who stood 6ft 4in and weighed 17st, he won the first of his six caps against Wales in 1937 and was one of eight Irishmen in the Lions party that toured South Africa the following year. There, he was in his element, playing in 17 of the 20 provincial matches and in the international series that the Lions lost 2-1.

Reports from the time refer frequently to the “outstanding Mayne”. One of his team-mates, the late Vivian Jenkins, described the Ulsterman as “a very quiet chap. At first glance you would think he wouldn’t hurt a fly, but we soon discovered that when steamed up he would do anything.” His last appearance in an Ireland shirt was against Wales in March 1939. Had not war intervened, he would undoubtedly have gone on to win many more caps.

But back injuries suffered in parachute jumps prevented him from resuming his sporting career after the war.

At the outbreak of war and after service with the Ulster rifles he transferred to the Commandos, from where he was recruited by David Stirling, the founder of the SAS. Mayne and his men wrought havoc behind German and Italian lines in North Africa. After Stirling’s capture, Mayne was appointed commanding officer of the 1st SAS Regiment. He won the DSO first in 1942 in Libya, then Bars in 1943 and 1944 in Sicily and France respectively.

It was his further action for which he was recommended for the VC. It took place on April 9, 1945 in Oldenburg in Germany. The SAS had been given the task of clearing a path for the Canadian armoured division. Their advance was stalled along a narrow road. Eight troops, three of them injured, were pinned down in a ditch by heavy machine and mortar fire.

Mayne was made aware of the gravity of the situation. He rushed to the scene. Grabbing a machinegun he single-handedly cleared one of the farm buildings. With a volunteer he drove a jeep up the exposed road three times under withering enemy fire.

Mayne’s jeep, its twin Vickers machineguns each issuing 1,100 rounds a minute, replied and drove back the Germans, killing many. As he passed his men to his left, he shouted: “I will pick you up on the way back.”

With the Germans now retreating but still laying down considerable fire, Mayne stopped to rescue the wounded men.

Sergeant Albert Youngman whose devotion to Mayne, with whom he served in the SAS for five years has never dimmed, was one of those trapped and expecting to die. “I saw Paddy carry out many brave actions but Oldenburg overshadowed everything,” Youngman, 90, said. “I genuinely thought I wasn’t going to make it. He was an unbelievable man and I owe him my life. It would be a fitting tribute to his memory if the award he so richly deserved could be upgraded. We are now in a situation where the brass have to admit they were wrong.”

The citation for the VC said: “There is little doubt that Mayne’s exceptional personal courage and leadership saved the lives of many men and greatly helped the Allied advance on Berlin.”

However, months later as the citation document shows, the letters VC have clearly been scratched out and next to it “DSO and 3rd Bar” written.

Quite why has never been properly established. Barry Abbott, whose mother is from Newtownards but who lives in Norfolk, has made it his mission to find out. “They told him he had won the VC,” Abbott said. “Six months later they took it away. That is wrong.” He believes the decision has much to do with the army hierarchy’s suspicion of the special forces as well as prejudice and spite.

Having studied documents obtained under the Freedom of Information Act he thinks the trail may lead back to Sir Colville Wemyss, the military secretary to the Secretary of State for War and who also sat on the Grant of Honours committee. Winston Churchill had replaced him with Sir John Dill as head of the British Army mission to Washington in December 1941, a decision with which he was deeply unhappy. When consulted by his deputy about the recommendation of a VC, which the Prime Minister supported privately, Wemyss decreed it should be downgraded.

This decision was outlined in a letter in July 1945 that set out that Mayne’s bravery was not a “single act of heroism” given that he had a volunteer with him. But nowhere in the warrant for the VC is it stipulated that this has to be the case. It stipulates only a “signal act of bravery”. After the war King George VI summoned Mayne to Buckingham Place and inquired why the VC had “so strangely eluded him”. Mayne replied: “I served to my best my Lord, my King and Queen and no one can take that honour away from me.”

His Majesty asked Churchill to investigate but nothing could be changed. Subsequent attempts to have the award made have been rejected on the basis that since 1946 it has been Government policy not to make awards retrospectively.

After the war Mayne, who never married, worked as a solicitor and as secretary to the Law Society of Northern Ireland. Nothing could replace the stimulus of war however. He drank ever more heavily and sunk into depression. He died driving his “red rocket”, his 2.5 litre Riley Roadster at speed into a railing and house. He is buried in the family grave at Movilla Cemetery. “The gift of leadership and the ability to inspire complete devotion and loyalty were his to an exceptional degree,” the padre at his funeral, the largest ever in Newtownards, said.