John Acland had a reputation in the Brigade of Guards for being outspoken and ridiculing anyone speaking pompously. He would never hesitate to challenge anything he judged ill-founded in argument, corrupt or inefficient. Despite a wicked sense of humour, he could be ruminative and morose when he encountered something with which he profoundly disagreed. Superiors and subordinates respected him, and approached him warily.

John Hugh Bevil Acland was educated at Eton and commissioned from Sandhurst into the Scots Guards in 1948. He went with 2nd Scots Guards to Malaya in 1950, and also served in Cyprus at the time of the Eoka terrorist campaign led by General Grivas.

In 1957 he became an apparently unlikely Equerry to the Duke of Gloucester, but proved an inspired choice. His refusal to see anything but the amusing side of any embarrassment did neither his master nor himself any harm.

After the Staff College and a stint of regimental duty, he was appointed brigade major (chief of staff) of 4th Guards Brigade in the Army of the Rhine in 1964. Working within a Guards environment, he adapted well to the close relationship with the divisional staff, helped by his down-to-earth approach and wit. When appointed to command 2nd Scots Guards in 1968 it appeared that his career was set on a straight course upwards. But his outspokenness led to trouble.

When it was announced that, as part of a defence review recommending a reduction in the number of infantry battalions, 2nd Scots Guards would either be disbanded or, as eventually temporarily became the case, reduced to single company strength, Acland wrote a letter to The Times arguing against any such decision. (He consistently maintained he had marked the letter “Not for publication”, but its purpose seems obscure under such a qualification).

The letter caused a disproportionate degree of excitement in the MoD and, seemingly to an even greater extent, within the Guards hierarchy. The Major-General Commanding the Household Division ordered Acland’s recommendation for a brigade command to be rescinded.

Acland bore this calmly as he took up a new job in the MoD that included responsibility for preparation of the annual review of the number of major-generals’ posts in the Army, without — of course — having any hand in who filled them. His own post, Colonel Army Staff Duties 3/5, was recognised as a make-or-break affair. But he quickly mastered its complexities and, despite the rescindment of his recommendation, was promoted brigadier to be Commander Land Forces and Deputy Commander British Forces in Cyprus in 1976.

Two years after the Turkish intervention in the north of the island, this was an interesting job with an elegant house overlooking the sea. Yet Acland appeared never quite to find his best form in Cyprus, grumbling to visiting friends about difficulties he had with the Commander British Forces. He was appointed CBE and promoted major-general to command the United Kingdom’s South West District in 1978.

This was not to be perceived as a springboard for further advancement, unless some stroke of luck provided an opportunity to demonstrate his abilities. This is exactly what occurred.

After prolonged negotiations, the black majority parties in Rhodesia reached agreement with the British Government and the white minority led by Ian Smith for Britain to resume responsibility for governing Rhodesia while elections were held. These had to include the guerrilla fighters of Zanu and Zapu who had to be persuaded to stop fighting and emerge from the forest.

In November 1979 Acland was selected to command the British Monitoring Force, reporting to the newly appointed Governor, Sir Christopher (later Lord) Soames. To avoid a large influx of British troops into an already tense security situation, the force to oversee the reception and accommodation of the guerrillas, then ensure the fairness of the elections, principally comprised the commanding officers and headquarters staff of field force units in the UK, together with detachments of British police. This plan proved highly successful, once the first guerrillas had been persuaded to leave the forest and hand over their arms, having been welcomed in a clearing by a British subaltern in charge of an outpost of only eight men.

Acland toured the outposts on the forest edge tirelessly, greeting the guerrillas and visiting them in their hastily erected camps to instil confidence in “the democratic process”. In Salisbury (now Harare), he was able to provide up-to-the-minute advice to the Governor in his capacity as chairman of the Ceasefire Commission. His relationship with Soames, not a man to welcome others’ counsel, proved effective. His relationships with the white hierarchy in Salisbury, many of whom felt their personal situation threatened, varied from intensely warm to coldly formal, but these were extraordinary times.

On return to London, Acland remarked that for once “God must have been on the side of the small battalions”, in reference to the minute detachments constituting the monitoring force. He was appointed KCB for his services.

Back at Headquarters South West District on Salisbury Plain, however, he fell into a ruminative mood over what he saw as neglect of the facilities and housing of the units under his command owing to Ministry of Defence cuts. The Under-Secretary of State for the Army, new in post and not well briefed, was given a startling reception during a routine visit.

Acland retired from the Army in 1981, observing that the job to which he had been appointed after his major-general’s command was no job at all. This was despite advice from friends that Senior Directing Staff (Army) at the Royal College of Defence Studies in London might be just a siding until something more challenging became available.

That said, it could hardly be helpful that his reputation for impulsive reaction to official policy was well known to the members of the Army Board.

For the next ten years he devoted much of his considerable energy to problems of alcoholism among young people, first as a director of research with Allied Vintners and later as chairman of the South West Working Party on Alcohol. He was Vice Lord-Lieutenant for Devon, 1994-99. While running his Devon farm, he was honorary colonel of Exeter University OTC, 1980-90; the Royal Devon Yeomanry, 1983-92; and the Royal Wessex Yeomanry 1989-92.

He was president of the Royal British Legion, Devon, 1982-90, a member of the Dartmoor National Park Authority and a trustee, Exeter Cathedral Preservation Trust.

He married Myrtle Crawford in 1953. Universally known as “Turtle”, she was an accomplished hostess. In particular, she handled with consummate sensitivity an occasion in Cyprus when Princess Margaret had flown in, having heard en route that her husband, Lord Snowdon, was to sue her for divorce.

Acland is survived by her and by a son and a daughter.

Major-General Sir John Acland, KCB, CBE, Commander UK Monitoring Force in Zimbabwe- Rhodesia, 1979-80, was born on November 26, 1928. He died on November 17, 2006, aged 77