[2] An amateur, McClintock also worked across the worlds of botany and horticulture, and organised a scientific survey of the natural history of Buckingham Palace Garden.

There were surprising changes of direction in his life: in one vacation from Cambridge he had, in the absence of her governess, to teach his younger sister botany, and found that the names of the plants stuck in his mind – a bent much developed later and accelerating after the war.

After an inactive winter he joined, in early 1940, a battalion of the Scots Guards recruited (largely of officers who had to resign their commissions) to fight with the Finns against the Russians.

Later McClintock worked in intelligence in Matlock, and in London, as a preparation for governing a defeated land: training police and firemen to serve in an occupied Germany.

In June 1944 McClintock crossed to Normandy soon after D-day; following the German retreat across northern France and the Low Countries, he said that he was sometimes advancing 100 miles in a day, without ever meeting resistance that required him actually to use the skill he had acquired as a gunner.

When McClintock turned up at the house, he was greeted with great distress, because Herr Schwarz had shot himself – being so emotionally affected at the military defeat, the subjection, and then – by contrast – a few hours of treatment as a fellow human being.

Their house, Bracken Hill, had a three-acre woodland garden, to which McClintock could not then give much time, but which twenty years later he developed to make the most of its features – sandy soil and shade.

[5] He was considered for secretary of the RHS, but there was a delay – in which time a friend offered him a job at the Coal Utilisation Council, where he remained until his retirement in the late 1960s.

Although he had no formal training in botany or in horticulture, nor indeed in any science, he became a self-taught specialist in many topics, including heathers and bamboo, and gained international recognition for his scholarship.

He did much to foster the belief that botany and gardening were not separate disciplines: for example, he was influential in the late 1970s in setting up the RHS journal The Plantsman, and was a regular contributor to its pages.

As part of this, to aid bridging the gap between botanists and gardeners he organised a joint conference in 1971 between the RHS and the Botanical Society of the British Isles (BSBI).

Inside the house, McClintock's library contained 4,000 books, his herbarium had 3,500 sheets of bamboos, and his card index of heather cultivars numbered 3,000 in non-digitalised form.

While botanising in Sicily (looking for Erica sicula [it]), McClintock fell down a scree mountainside near Trapani, requiring transportation by helicopter to hospital in Palermo, where he had 40 stitches.