Billy Arjan Singh: Hunter of India's big cats who became a passionate and award-winning conservationist

An uniquely tenacious champion of India's big cats, Billy Arjan Singh devoted 50 years to the conservation of tigers and leopards. Yet as a boy he had been a bloodthirsty killer, gunning down every animal in sight.

He was a scion of a princely Sikh family, the Kapurthalas, and because his father managed a huge estate at Balrampur, some 150 miles north-east of Lucknow, he grew up among the great forests of Northern India, in a place where people shot big game as a matter of course. He killed his first leopard at the age of 12, his first tiger at 14. His fascination with wild animals was increased by the fact that in Nainital, the Himalayan resort where he went to school, he sat at the feet of the legendary hunter-naturalist Jim Corbett, and heard at first hand the stories which Corbett later published in his book Man-Eaters of Kumaon.

Billy's family had strong English connections. His father Jasbir Singh went to Balliol, and he himself hoped to go to Oxford, but in the event had to be content with Allahabad University. Encouraged by his father, who had a passion for wrestling, he took to body-building and developed a formidable physique.

When war broke out in Europe in 1939, he volunteered for military service, hoping to travel abroad. Travel he did – but only to Iraq – and although he trained as a gunner, he never saw action. After the war he decided to try farming, and rented 750 acres of land in the district of Kheri. For the next nine years he lived in a grass hut, battling to protect his crops from the deer and wild boar that swarmed in the virgin grassland around his holding.

Every Christmas he, his two brothers and other members of the family would rent a shooting block and camp in the jungle, where tigers and leopards were still their most prized quarry. Then, one night, he experienced a Damascene conversion, when he shot a leopard in the lights of his vehicle, but then felt a sudden revulsion, and vowed from that moment to protect India's dwindling wild animals rather than hunt them.

Feeling hemmed in by other farmers who had settled round him, he headed off across country to the north on his elephant Baghwan Piari, and discovered a magical spot on the bank of a river, with jungle rising in a solid wall from an escarpment on the far side. There, as far from civilisation as he could go, he decided to settle. Again he made do for a while with a grass hut, but later he built a long, low house which he called Tiger Haven, and there he remained for almost the whole of his life.

In his youth he had courted girls with enthusiasm, and had been engaged at least once. Now, however, he realised that he could not expect any woman to share the kind of existence he wanted, out in the wilds, and he resigned himself to life as a bachelor. All his energy went into his new role as an unpaid, freelance wildlife warden. His first major success was to save a herd of barasingha (swamp deer) – an achievement for which he was awarded the World Wildlife Fund's Gold Medal in 1976. Also, with the backing of the Prime Minister, Indira Gandhi, he was largely responsible for the creation of the Dudhwa National Park – a 200-square mile expanse of forest and grassland on the border of Nepal, and now one of India's 23 tiger reserves.

At home, on the edge of the park, he began experiments with big cats, bringing up an orphaned male leopard cub, which he called Prince, and then two females, Harriet and Juliette. Never caging them, he allowed them the run of the house and its environs, his aim being to see if instinct would make them take to the jungle, and thus augment the dwindling wild population. Prince did just that, and Billy formed an astonishingly close relationship with Harriet, whom he loved more than any human. But to his great grief both she and her sister died prematurely, poisoned by local farmers.

By then – again with Gandhi's backing – he had fetched a tigress cub from a zoo in England, and he brought her up in the same way, taking her for daily walks in the jungle and teaching her to hunt. When Tara went wild and produced a litter of cubs in the forest, he counted his experiment a triumphant success, claiming that she would do wonders for the Dudhwa tigers by refreshing the local gene pool.

The babus (bureaucrats) of the Forest Service thought otherwise. Discovering that Tara was not a pure Bengal tiger, but had Siberian genes in her ancestry, they denounced Billy for having introduced a "genetic cocktail" into the Indian jungle, and called for her immediate extermination. Luckily they had no hope of finding her.

Soon another threat loomed. In a sudden outbeak of man-eating, the Kheri tigers killed over 120 humans. For every fresh outrage Tara was blamed, on the grounds that her peculiar upbringing had left her without a tiger's normal fear of people. Again and again Billy was faced with the task of having to shoot a man-eater: every time, he dreaded finding that it was Tara – but it never was. She survived, and in due course raised four litters.

Billy's resolute defence of the National Park and its creatures, and the uncompromising honesty with which he hounded corrupt forest officers, made him many enemies. Although co-opted on to various official committees, he remained an outsider. Diplomacy was never his suit: once he hitched an intruder to the back of his jeep and towed him bodily away; another time, in my company, when he found two men stealing firewood, he flattened them, right and left, with swingeing blows that sent them spinning to the jungle floor.

He published several books about his animals, but his style tended to be excessively scientific, and needed much elucidation by editors. For some years, helped by his brother Balram and sister-in-law Mira, he took in a few tourists. Visitors to Tiger Haven had the joy of living with an Indian family, waited on by a small army of servants, in a magically remote place 10 hours' drive from Delhi, looked after by a host who could quote Wordsworth and Shakespeare as freely as Kipling. Although merciless in combat with the babus, at home he was gentle and charming, full of nipping, rather childish jokes.

Yet his prime concern was always to protect the animals and their environment – and it was wonderfully fitting that in 2004, his 88th year, he was awarded the annual J. Paul Getty prize – almost the equivalent of a Nobel prize for conservation – in acknowledgement of his lifetime's work. By then he had walked thousands of miles through the jungle, tracking the big cats armed only with a stick, and he attributed his survival to the fact that they took him for a true denizen of the forest. They had come to see him (he thought) as a kind of honorary tiger, and accepted him as one of their own.

He died peacefully at home on New Year's morning. In accordance with his own wishes, his body was cremated on a pyre at Tiger Haven, and his ashes were buried among the graves of his beloved animals.

Duff Hart-Davis

Kunwar 'Billy' Arjan Singh, conservationist: born Gorakhpur, Uttar Pradesh, India 15 August 1917; U.P. World Wildlife Fund Gold Medal, 1976; J. Paul Getty Prize for Conservation, 2004; died Jasbirnagar, Uttar Pradesh 1 January 2010.