Publisher of military history books and husband of Jilly Cooper
Leo Cooper, who has died aged 79 after suffering from Parkinson's disease, was a publisher with a zeal for military history, who also enjoyed some notoriety as the husband of the novelist Jilly Cooper.
Leo's hospitality was out of all proportion to the size of his establishment. Every day, for 20-odd years, he kept open house at his "branch office", the Oporto pub in London's Covent Garden, where the company might include anyone from a general to a dustman. You might not have Leo to yourself for more than a minute or two – he really did do a lot of business at the bar – but you could always be sure of a drink.
Indeed, given Leo's appetite for company and a glass, it was, said the military historian Sir John Keegan, astonishing that he achieved anything serious in life. Yet he did. Were it not for Leo, the list of those "which have no memorial" would be far longer. Too nice a man to have made a successful soldier himself (though he did command a transport platoon during the Mau Mau uprising), Leo thought that those who had been at the sharp end deserved to have their say.
So, although his publishing business was based upon monumental works such as Lord Anglesey's eight-volume History of the British Cavalry (1973-95) and the Famous Regiments series, he was always on the look out for what George Orwell called "unofficial history", such as Antonia Hunt's Little Resistance (1982), the extraordinary story of an English schoolgirl's experiences in German-occupied France.
The first world war was a particular hobbyhorse of Leo's; every year, on the way to the Frankfurt book fair, he would take a brief tour of the battlefields. In winter he sometimes wore a sawn-off khaki greatcoat that could well have seen service on the western front.
A Yorkshireman (born in Settle), though this was not immediately apparent, he left school – Radley college in Oxfordshire – with more sporting colours than O- and A-levels, and after national service in Kenya, arrived in London in search of a job. That he found one at the publishers Longman was thanks to his aunt Lettice Cooper, the novelist, who with her sister Barbara gave him an entree to Fitzrovia.
Leo served a long apprenticeship at Longman and then went to work for André Deutsch, a hard taskmaster from whom he learned more in six months than in 10 years at Longman. His next employer was the equally autocratic Jamie (Hamish) Hamilton, who once told Leo that he proposed to sack someone "because I can't stand his wife". Jamie took a keen interest in his employees' wives, as Leo once discovered when he arrived home early from a business trip. He had just greeted Jilly when the doorbell rang; it was Jamie, carrying two bottles of champagne.
After this, Leo's days at Hamish Hamilton were numbered, but when he left, in 1968, to found Leo Cooper Ltd, he took with him the Famous Regiments series he had founded. Like generals, small publishers need luck. And to begin with, Leo was lucky. The illustrator Tim Jacques designed a striking emblem for him incorporating a crossed sword and pen. He acquired an exemplary editor and partner in Tom Hartman, whose eye for a solecism was as sharp as his appetite for gossip, plus a nucleus of loyal and diligent staff. And within a year or two of starting up he had published two classic war memoirs, Alex Bowlby's The Recollections of Rifleman Bowlby (1969) and John Goldsmith's Accidental Agent (1971).
But small publishers also need capital, and it was his want of this that forced Leo into a series of mergers, including one with Beatrix Potter's publishers Frederick Warne, that all ended in tears. Ironically, most of the firms he merged with also came to grief, a process he ascribed to "the curse of Cooper". He ended up as he began, virtually single-handed, until finally one author too many tried his patience too far and he dismissed himself, saying: "I'll soldier no more."
Leo had married Jilly (nee Sallitt) in 1961 following the break-up of his first marriage, to Diana, his former housemaster's daughter. Jilly made her name writing about marriage à la mode in the 60s and 70s, and there must have been many who assumed that only someone in a rock-solid relationship could mine it every week for copy. But in 1990, in the Guardian, Sarah Johnson, a publisher, revealed that for six years she and Leo had been having an affair. She had been driven to spill the beans, she said, by Jilly's habit of boasting in print about her perfect marriage. The fallout was considerable and for a time Leo and Jilly were semi-detached. But in the end they made it up.
A keen sportsman, who played rugby into his 40s and cricket for even longer (at Radley he was a contemporary of the future England captain Ted Dexter), Leo had the misfortune to develop Parkinson's disease, which he bore with his customary good humour. His very amusing memoirs, All My Friends Will Buy It: A Bottlefield Tour (2005), should be read by anyone contemplating a career in publishing, particularly the pages devoted to launch parties; but you would never guess from them how many people, myself included, he helped out in difficult times.
Jilly survives Leo, as do Laura, his daughter by his first wife, and Felix and Emily, the children he and Jilly adopted.
• Leo Cooper, publisher, born 25 March 1934; died 29 November 2013