[6] The outbreak of the Second World War gave him an excuse to return to Britain, where he enlisted as a private in an anti-aircraft battery under the command of Sir Victor Cazalet.
Rising through the ranks, he was transferred to military intelligence, given a commission and spent the latter part of the war as a member of the British army staff at Washington.
He would eventually establish himself as one of the leading biographers of his time; his first effort in this direction being a two-volume biography of Monckton Milnes that appeared in 1949 under the titles The Years of Promise and The Flight of Youth.
In 1970, he took out Irish citizenship and went to live at Banagher in County Offaly,[7] where he took rooms at the Shannon Hotel, and during the next few years produced authoritative biographies of both Anthony Trollope and Robert Louis Stevenson.
[12] His "natural rebelliousness was accentuated by his unremitting homosexuality" according to James Lees-Milne, but while physically attracted to his own sex he loved the companionship of women, and was sought after by hostesses for his sparkling conversation.
[13] He was a heavy drinker, and frequented back-street bars and shady pubs where he mixed with a rough crowd, associations that eventually contributed to his death when he was brutally killed on 25 January 1974 in his London flat, at 9 Ladbroke Grove, by three young men.
[14][15][16] However the three young men involved were jailed for manslaughter; their sentences were reduced on appeal as he had only suffered superficial injuries and died from choking on his own blood from a lip wound.