In May 1945, Osborn was serving with Tactical HQ 2nd Army in the closing phase of the campaign in Germany. He learned that someone bearing a close resemblance to Himmler, the head of the Nazi SS, had walked into an interrogation centre in an effort to find refuge or surrender to the Allies.

It was vital that the man be identified and, if necessary, secured. Osborn drove straight to the centre where, through an interpreter, Himmler confirmed his identity and stated that he wished to surrender; he also maintained that he alone could save what was left of Germany to fight alongside the Allies against Russia, and that he had vital information which he would disclose only to Montgomery.

The man refused to wear battledress on the ground that it was enemy uniform, so he was stripped, wrapped in an Army blanket and bundled into Osborn’s staff car.

Osborn drove to Army HQ as Murphy, with a drawn revolver, rode in the back with their prisoner. On arrival Himmler was escorted to a room where a doctor was waiting to carry out a preliminary examination to check that he was not carrying any poison.

As Osborn left the room to telephone the Army commander, he heard a shout and the sound of a scuffle. On coming back in he saw Himmler writhing stark naked on the floor, foaming at the mouth. He had concealed a small phial of poison under his tongue.

Michael Ashby Chadwick Osborn was born at Kingston upon Thames on July 28 1917 during a Zeppelin raid. Three months earlier his father had been killed in action at Salonika. Soon after he was born Mike was diagnosed with TB and the family moved to Switzerland, where they lived until the stock market crash of 1929, which left them almost destitute.

He was educated at Chillon College, Montreux, and, after the family moved to Kent, Cranbrook School. In 1937 he was commissioned from Sandhurst into the West Yorkshire Regiment (WYR) and posted to the 1st Battalion in India.

He and his brother officers got up to all sorts of pranks. One young subaltern, who was easily taken in, suffered badly from prickly heat in the hot weather. He was told that the cure was to stand naked in the first deluge of the monsoon.

This happened to coincide with an important guest night. After dinner, the CO led the principal guest out on to the veranda to cool off. There, to their intense embarrassment, they were confronted by the unadorned figure of the young man in all its glory.

A spell in Cairo was followed by a posting to 2 WYR in Khartoum. Osborn was orderly officer when the Italians, flying almost at head height, bombed the airfield near the barracks, and he was reprimanded by his CO for engaging the lumbering bombers with his revolver.

In March 1941, in the campaign in Eritrea, he was in command of a company of 2 WYR which attacked and captured Dologorodoc Fort in operations near Keren. The Italians believed that the strongly defended mountain fortress was impregnable.

A few days weeks later, in another attack, the leading troops checked when they came under heavy artillery, mortar and machine-gun fire. Osborn rallied them, the assault was resumed and 450 prisoners captured. He was awarded an MC.

There were some curious incidents in the campaign in Italian East Africa. A family of baboons regularly followed the patrols in the tall elephant grass and were deterred only when firing broke out. Near Asmara, a large sum in Italian lire was captured – but there was an acute shortage of lavatory paper and the money had to be used instead.

After a spell in Cyprus, in February 1942 Osborn returned to Alexandria for the defence of Tobruk. Moving at night with no transport, he and his men were continuously harried by the Germans. Two pints of water per man per day had to suffice for drinking and washing.

By June, Osborn was a major in command of a company of 2 WYR. In the disastrous operations to relieve Tobruk, known as the Battle of the Cauldron, he came under fire from 15 tanks, but succeeded in keeping his unit intact.

Six weeks later, at Ruweisat Ridge, an outpost of the Alamein Line, his company came under intense shell fire and several dive-bombing attacks. The citation for Osborn’s DSO paid tribute to his outstanding gallantry, and stated that his men took their objective in magnificent style and held it until relieved.

In the action Osborn was hit in the head by a bullet. He said afterwards that he owed his life to his batman, who had handed him his steel helmet and insisted he put it on before going forward to his leading platoon, which was being savagely attacked.

After recovering, Osborn attended Staff College, Haifa, and was then posted to HQ 50th Infantry Division in time to take part in the Battle of Mareth. The invasion of Sicily followed. When his Jeep sustained a near hit from a shell, he was blown into the road; his driver was killed.

Evacuated to London and pronounced fit again, in September 1943 he was posted to the War Office, where he was one of a small group entitled to read the Enigma decrypts.

In April 1944 he joined the staff of HQ Second British Army at Portsmouth, where he was involved in the final planning for D-Day. He and his colleagues worked such long hours that they had to take Benzedrine tablets to keep awake. His immediate superior was Colonel Selwyn Lloyd, a future Chancellor of the Exchequer and Foreign Secretary; in 1950 he was best man at Osborn’s wedding.

Osborn landed in Normandy on D+1 with Tactical HQ, Second Army.

Early in 1945, as the advance into Germany gathered pace, puzzling reports were received from Ultra and other sources which raised suspicions that there was a belt of typhoid through which the leading troops would have to pass.

Osborn was sent forward by General Dempsey, the Army commander, to meet the divisional CO and report back. He thus became one of the first people to uncover the hitherto unknown Belsen concentration camp. Typhoid had struck the camp, and Osborn lost no time in getting back to Army HQ and raising the alarm.

He subsequently liberated from a PoW camp his brother, Myles, who had been shot down flying a Swordfish at the Battle of Matapan. They had not set eyes on one another for years.

After the German surrender Osborn moved to Burma. He was appointed second-in-command of 1 WYR and joined them south of Mandalay as they were pushing the Japanese southwards.

When the Burma campaign ended, after a spell in Indonesia and Malaya in command of 2 WYR he was posted to northern Greece for a year of operations against the communist insurgency. He was appointed OBE in 1948.

A year with the regiment in Vienna as part of the occupation force was followed, in 1950, by his appointment as deputy military assistant to the CIGS, Field Marshal Sir William Slim. During his two-year tour the Russians made a rather clumsy attempt to recruit him as an agent.

He then returned to Malaya with the West Yorkshires to combat the communist terrorists and took command of the 22nd SAS Regiment for almost a year after the previous CO was injured in a parachute drop. He was mentioned in despatches.

He became an instructor at Staff College, Camberley, before moving to the Canadian Staff College at Kingston, Ontario. Returning to Malaya in 1958, at the request of General Sir Gerald Templer, he commanded the newly-raised 1st Battalion the Federation Regiment.

Osborn attended the Imperial Defence College before moving to HQ 1 British Corps in BAOR. There he suffered a court martial which, though he was ultimately acquitted, proved highly damaging to his career.

The charges, of indecent assault, were brought by a 15-year-old boy who had entered Osborn’s rooms. Osborn was found guilty, despite his defence QC pointing out inconsistencies in the boy’s account. The conviction was quickly overturned on appeal and Osborn was fully reinstated to his former rank; but, convinced that his prospects had been doomed by the case, he took early retirement.

Osborn bought land on the Greek island of Skiathos, building a house there and encouraging his friends to do the same as he and his wife developed a successful villa rental business.

In 1978 he returned to England and settled in Dorset. He kept a flat in London and played a notable part in the affairs of the Ex-Service Fellowship Centre.

Mike Osborn died on January 15. His wife, Anita, survives him with their son and a daughter.