At Oxford, Howard was part of the Railway Club, which included: Henry Yorke, Roy Harrod, Henry Thynne, 6th Marquess of Bath, David Plunket Greene, Harry Fox-Strangways, 7th Earl of Ilchester, Michael Parsons, 6th Earl of Rosse, John Sutro, Hugh Lygon, Harold Acton, Bryan Guinness, 2nd Baron Moyne, Patrick Balfour, 3rd Baron Kinross, Mark Ogilvie-Grant, and John Drury-Lowe.

In the late 1920s, he was a key figure among London's "Bright Young Things"—a privileged, fashionable and bohemian set of relentless party-goers, satirised in such novels as Evelyn Waugh's 1930 Vile Bodies where the character of Miles Malpractice owes something to Howard.

In 1929, he was famously involved in the "Bruno Hat" hoax when the fashionable Hon Mr. & Mrs. Bryan Guinness promoted a spoof London art exhibition by an apparently unknown German painter Bruno Hat (impersonated by the German-speaking Tom Mitford, brother of Nancy and Diana Mitford—the latter at the time Mrs. Guinness, a socialite, arts' patron and friend of Howard, Lytton Strachey, Evelyn Waugh, Boris Anrep, Dora Carrington, John Betjeman and other artistic and literary figures—before her second marriage to British fascist leader Sir Oswald Mosley).

Howard is credited with coining the phrase, "Anybody over the age of 30 seen in a bus has been a failure in life", often wrongly attributed to Margaret Thatcher.

Subsequently, he led a very active social life, tried to come to terms with his homosexuality, and published only one substantial poetry collection God Save the King (1930, Hours Press).

Transferred to another posting, where he referred to his commanding officer as "Colonel Cutie" (an appellation Evelyn Waugh gave his rebellious rogue Basil Seal in the novel Put Out More Flags), Howard was dismissed in December 1944, by which time he had formed a longstanding open relationship with Sam Langford, an Irishman serving in the Air Sea Rescue.

Because of drinking, drug use, and sexual indiscretions, they were expelled in turn from Monaco, France, Italy and Spain, the French authorities noting their "moralité douteuse" (dubious morality).

He suffered from bad health in the 1950s, and committed suicide by taking an overdose of sedatives after the death of his lover, Sam Langford (1926–1958), who died suddenly but naturally in Howard's bath.