On April 1944 a bombing raid on coastal defences near Deauville was reported to have set off a series of flashes on the beach. Four reconnaissance operations, code-named Tarbrush, were therefore mounted at short notice to examine mines and obstacles in the region — though not on the D-Day beaches themselves for fear of attracting attention to them.

In May, Smith was called to Combined Operations HQ for a top-level briefing. His orders were to find out whether explosive devices had been attached to the tops of stakes that the Germans had erected on the beaches. If they had, when detonated they might buckle the doors of the landing craft and the soldiers trapped inside would be sitting targets.

On the moonless night of May 16, Smith, at the head of a small detachment of 10 (Inter-Allied) Commando, embarked from Dover in an MTB. Their engine-powered dory was dropped a mile offshore and they landed by dinghy east of Calais.

Armed with a Sten gun and accompanied by a sapper, Smith crawled up the beach. The smell of cigarette smoke alerted them to the presence of a sentry. Then they heard German spoken. The guard was being changed.

The sapper groped his way up one of the stakes and found an anti-tank Teller mine nailed to the top. Having decided not to remove it because the sentry would be sure to hear the noise, they returned to their dory, slid over the side and paddled until they were far enough from the beach to start the engine.

They transmitted their call sign by “S” phone, an early “walkie-talkie”, but received no answer from the MTB. A ship approached them and, turning on its searchlight, scanned the sea. The Germans permitted no fishing at night, and Smith feared that it was one of their armed naval trawlers.

They flattened themselves on the bottom of the dory. The vessel sailed past only a few yards away, and Smith said afterwards: “How it did not see us, I shall never know.” Some minutes later it turned about and, directed by its radar or shore radar, loosed off some heavy gunfire in their direction.

Just as it was getting very close there came a sudden ringing of bells and shouted orders and, having apparently become stuck on a sand bank, it stopped. Smith and his party eventually found the MTB, which had moved out to sea to avoid the trawler. Smith celebrated the success of the operation in a series of Dover hostelries and became so inebriated that his batman had to take him home in a wheelbarrow. He was awarded a Bar to an earlier MC.

Ian Christopher Downs Smith was born at Keynsham, near Bristol, on April 22 1920 and educated at Wycliffe College. In 1939, as a cadet at Sandhurst, he was one of a party taken to Aldershot to see an armoured division. Interspersed with a few tanks were soldiers holding up green flags. When asked what they were doing, they sprang to attention and replied: “I am a Mark II Tank, sir.”

Smith played rugby for Sandhurst, Harlequins and the Army. Shortly after being commissioned into the Royal Army Service Corps, he volunteered to join No 2 Commando, the precursor of the Parachute Regiment, later termed the 1st Battalion Parachute Regiment, and trained at Ringway, where he and his comrades were reviewed by a disgruntled Churchill who was counting on getting many more volunteers.

In 1940 he moved to Lochailort in Scotland, where he was trained in unarmed combat, pistol shooting and explosives. A spell at Achnacarry as an instructor in fieldcraft was followed by a posting to No 12 Commando. He then moved to Shetland to work with a Norwegian motor torpedo boat flotilla and was based at Sullom Voe.

On reconnaissance missions to spy on the shipping in Norwegian territorial waters, they set off from Lerwick and hoisted the German naval ensign as they approached the coast. After creeping down a narrow channel in the cliff face, they docked, camouflaging the boat during the hours of daylight.

Smith was then ordered to the Isle of Wight, where he became part of Fynn Force, based at Freshwater Bay. In September 1943 he was part of a small unit that was landed between Dieppe and Le Havre to report on the enemy’s coastal defences. Forbidden to use radio signals, they were provided with carrier pigeons to send back their information. But when they released one of the birds, it was promptly killed by a peregrine falcon; a second pigeon met the same fate.

In December that year Smith and a small group embarked at Newhaven and crossed the Channel in an MTB on a reconnaissance mission. They landed on the north coast of France near Criel-Sur-Mer and had a difficult climb to the top of the cliff. Smith returned with valuable information on the German defences, but on the way back to the MTB they were almost cut off by a fast-moving enemy convoy, and Smith needed all his navigating skills to elude it. He was awarded his first MC, the citation stating that he had led eight previous operations of a similar type.

Shortly before D-Day, Smith was recruited by the SOE and flew to Italy. In Bari, he was told that he was to be dropped into Yugoslavia to join Brigadier Fitzroy Maclean’s mission and serve as British Liaison Officer with the 5th Partisan Corps in Bosnia.

As he parachuted down, he heard a voice call out: “In a hurry, are you sir?” It was Corporal Nash, his signaller and bodyguard, whom he had overtaken because he was much heavier. Sharing a nomadic life in the mountains with the partisans, he was constantly on the move dodging enemy patrols as he arranged for supply drops of food and arms, called in air support when an attack was launched against the Germans and helped evacuate those who were badly wounded or downed American airmen.

On the way back to Bari in a Tank Landing Ship, Smith was enjoying a shot of Navy rum with the boatswain when the steel walls of the cabin bent inwards as if they had received a blow from a gigantic hammer. A Liberty ship, loaded with thousands of tons of high explosives had blown up, causing devastation in the Italian port and great loss of life.

Smith was then attached to the Special Boat Squadron and commanded a small force in Crete. Living in a large cave and based in the east of the island, their task was to watch the remnants of the German and Italian occupiers and report back to their base.

A spell on the Greek mainland, followed by a raid on the Dalmatian island of Cres, brought Smith’s active service to an end. When the war ended, he was promoted to major, and after commanding an RASC unit at Bicester he went up to Jesus College, Cambridge, to learn Russian.

He was then posted to Minden in western Germany, where he interrogated deserters from the Soviet forces who were suspected of being agents posing as refugees. In 1947 he joined the family textile business at Stockport, Cheshire, eventually moving with the firm to Wales. He then managed a hotel for five years. In the 1970s he moved to Co Donegal, where he started a fish farm.

In August 1974 Smith was driving a car near Randalstown, Northern Ireland, when he was forced to stop by three armed masked men. They tied him up, put a bomb in his car and then ordered him to drive into town and park by an electrical shop. They told him that they would follow him and shoot him if he did not do what they wanted and that the bomb was timed to go off in 20 minutes. At the shop there were several members of the RUC, who told him not to stop but to drive out of town. He found a field, left the car and ran for his life. The bomb exploded on time.

Smith spent the last decade of his life in Northern Ireland. Watching rugby matches was his favourite recreation.

Ian Smith married, in 1944, Margaret (Peggy) Cropper. She predeceased him, and he is survived by their son. A daughter predeceased him.

Major Ian Smith, born April 22 1920, died May 3 2012