Sixteen years after winning the inaugural Monaco Grand Prix in 1929, William Grover-Williams was executed by the Nazis at Sachsenhausen concentration camp.

Bravery has been watered down in the modern world of sports, too often used as a throwaway label to describe a plucky loser who refused to lie down in the face of stronger opposition. But the word in its true meaning can be used to describe Grover-Williams two-fold; on the one hand, he raced at a time when the line between victory and death was barely recognisable; on the other, he became a secret agent and resistance fighter deep inside occupied France during the Second World War. It was the latter he would pay for with his life.

Born to an English father and a French mother, Grover-Williams caught the motor racing bug at 15 after buying a motorbike. Very quickly he started competing in and winning motorbike races and rallies, albeit after lying about his age and under the name "W Williams" to ensure his mother never found out about his dangerous new hobby. He soon became a chauffeur for Irish painter Sir William Orpen and by 1925 had somehow raised enough funds to buy a Bugatti Type 35, with which he set about making a name for himself as Britain's leading driver of the decade, a talented pilot with a penchant for frightening bravery and speed.

One story of Grover-Williams' early notoriety involves his wife, Yvonne Aupicq. One of the pair's favourite pastimes was racing around their hometown of Monte Carlo in Hispano-Suizas. Police would frequently pull over Yvonne but never her husband and, the story goes, when his wife protested to a policeman in 1929 he told her: "He is Williams. We don't stop Williams."

Later that year he won the first race around those same streets, beating heavy favourite Rudolf Caracciola in a privately-entered Bugatti painted in British racing green. It was no flash in the pan; Grover-Williams had won the French Grand Prix a year earlier and would repeat the feat again in 1929. His victory at the 1931 Belgian Grand Prix was his only significant result in the European Championship but the last for a Brit until Richard Seaman won for Mercedes in Germany seven years later.

Retirement followed in 1933 after three consecutive victories at the La Baule Grand Prix. But his peaceful life after motor racing was shattered when the Second World War broke out six years later. Grover-Williams answered England's call and became a chauffeur for senior British officers. Fittingly for the most successful English driver of his generation he had soon pulled off a hair-raising escape to Cherbourg via Brittany after he and a group of officers had been cut off from the evacuation of Dunkirk by the advancing Nazis.

National Motor Museum/Heritage Images/Getty Images

His exploits saw him picked up by the Special Operations Executive (SOE), which had been tasked by British prime minister Winston Churchill with "set[ting] Europe ablaze" through subversive warfare. Grover-Williams' bravery and fluent French made him a natural candidate. His first task was to set up an SOE network - his was to be known as Chestnut - around Paris.

On May 30, 1942, Grover-Williams was dropped over France under the cover of darkness. Initially he had to endure a frustrating wait for more agents and radio equipment to arrive from Britain. During this time he rekindled a friendship with old racing rival Robert Benoist - France's top driver of the 1920s - and the pair worked together to sabotage German efforts in the area, as well as recovering weapons and agents dropped around Paris as the network finally began to get the resources it needed. Benoist's story is equally fascinating and central to Chesnut - the exploits of both he and Grover-Williams are detailed in Joe Saward's 'The Grand Prix Saboteurs', the most comprehensive tale of the remarkable pre-war-racers-turned-spies.

Grover-Williams was eventually caught and arrested by German soldiers in August 1943 after the Germans infiltrated the Chestnut network. Benoist had escaped from his house, the scene of Grover-Williams' capture and arrest, but, after briefly escaping safely to England, returned to France and was finally apprehended and then executed at Buchenwald in September 1944. Despite rigorous torture by the Gestapo, Grover-Williams gave his interrogators nothing. He was eventually transferred to Sachsenhausen where he was immediately placed in solitary confinement. One guard would later remark the former racing driver received "the most brutal treatment" at the hands of his captors.

With defeat looming in early 1945 the Nazis set about executing prisoners to cover the tracks of their atrocities, with Grover-Williams' name included on a list of political prisoners to receive special treatment. A witness later told investigators he had last seen Grover-Williams between March 15-18, adding that he was executed either by hanging, shooting or lethal injection - the exact details remain a mystery. The proximity of his death to the end of the war is more obvious; within two months the Red Army had liberated Sachsenhausen, Adolf Hitler had committed suicide and Germany had surrendered.

It would be unfair to say Grover-Williams has become a forgotten figure in British and motor racing history but his exploits have not received the reverence and fame they should have. Seventy years on, just weeks after the anniversary of Victory in Europe (VE) Day and on the eve of the 73rd edition of the race he won before anyone else, his life sounds as remarkable as it must have done in 1945.