As literature director of the Arts Council of Great Britain during one of its most turbulent periods, Charles Osborne, who has died aged 89, will be remembered by many for his coruscatingly witty memoranda and public responses to criticism of his often controversial policies. But he was also an impressively protean writer, equally at home in biography, journalism, poetry, music, drama and literary criticism.

His writings included studies of the operas of Verdi (for which he had a particular penchant), Wagner, Strauss and Mozart, a biography of WH Auden, and a biographical companion to the works of Agatha Christie. He also had considerable success converting plays into novels, three by Christie (translated into many languages), Noël Coward’s Blithe Spirit and Oscar Wilde’s The Importance of Being Earnest among them.

From 1966 to 1986 he worked for the Arts Council, initially as assistant to the literature director, Eric Walter White, taking over as director in 1971. Given his irrepressibly maverick nature he was an unlikely bureaucrat (the subtitle of his 1986 autobiography, Giving It Away, was Memoirs of an Uncivil Servant), and his incumbency was marked by a good deal of tragicomic skirmishing in the world of belles-lettres.

Essentially Osborne was in favour of reducing grants to individuals – there was a danger of the Arts Council becoming a “literary soup kitchen”, he believed – and making them instead to institutions. He floated the idea of a national publishing house to support non-commercial projects, but was more successful in launching a series of annual poetry anthologies, in which the work of several hundred largely unknown poets was published by the Arts Council.

Inevitably he came into conflict with disappointed individuals, as well as writers’ unions, and his habitually acrid rejoinders to correspondents made him many enemies. When his autobiographical account of his tenure was about to be published, Lord (Arnold) Goodman, former chairman of the Arts Council, opined that: “If everyone to whom you have sent an offensive postcard buys a copy, you will be a richer author than Jeffrey Archer or Barbara Cartland.”

Opposed to the idea of state support for community arts, whether it be the Notting Hill carnival or local writing workshops, Osborne unapologetically diverted funds to professional writers, often via bodies such as the Poetry Society and the Poetry International summer festivals, and with Patrick Garland presented the latter festivals in the late 1960s with a roster of what reads like a Who’s Who of distinguished international poets.

He was opposed equally vehemently to the performance art of the 70s, which he characterised as “harmless lunatics wandering across East Anglia with poles on their heads”. Intolerant of mediocrity, he unashamedly championed “elitism” in the arts, bringing him into conflict with the wave of diversity, inclusion and widening access to the arts then beginning to sweep through the corridors of 105 Piccadilly.

Following the Arts Council’s organisational review of 1984, the results of which were published in a booklet entitled The Glory of the Garden, the axe fell on the literature department – its budget of just under £1m was to be halved – and Osborne was effectively made redundant.

Born in a suburb of Brisbane, Australia, he was the son of Vincent, a solicitor from Barnstaple, Devon, and his wife, Elsa, from Vienna, Austria. A precocious only child, Charles taught himself to read by studying his father’s newspaper every morning, soon ploughing through the complete works of Charles Dickens and other classics. He also taught himself to play the piano at the age of five, eventually acquiring a competent technique and seizing opportunities both to play the harmonium at the local Methodist church and to sing.

At the age of 18 he took singing lessons from an Italian baritone, Vido Luppi, following up with tuition from various individuals, notably including Joseph Browning Mummery, who had sung Rodolfo to Nellie Melba’s Mimi in La Bohème at her Covent Garden farewell in 1926. Mummery tactfully steered him away from opera and lieder, guiding him towards operetta and musical comedy, where he might be able to exploit the talent for acting he had already discovered.

It was indeed acting that was to support Osborne throughout his 20s: he appeared in everything from Shakespeare to Coward in the theatres of Brisbane, Melbourne and beyond, and played rep in Ned Kelly country. He was also a fluent poet, and on occasions when he forgot lines on stage was able to compensate by improvising in impeccable blank verse. He appeared in radio plays, serials and commercials and after winning a competition on one tour for having the most shapely legs in the company, earned extra cash by posing nude for a life class at the National Art Gallery of Victoria in Melbourne.

In 1953, aged 25, he set sail for Britain, initially taking casual jobs, including as a commissionaire at the Academy cinema in Oxford Street, London. His insistence, however, on wearing his cap at what he considered “a suitably insouciant angle” resulted in him being fired. He lodged for a while in the largely Australian menage of the music critic Felix Aprahamian in Muswell Hill, north London. In London and the regions there were plentiful opportunities to tread the boards and a more than passing facial resemblance to Marlon Brando was noted. He played a bit part (pilot officer Foxlee) in Michael Anderson’s 1955 film The Dam Busters: it may only have been two or three lines, but the Aprahamian household was impressed when a car arrived for him.

He was introduced by his host to leading musicians of the time, including the baritone Gérard Souzay and violinist Manoug Parikian, and built up a core of freelance contacts in the musical world. Soon he was writing record sleeve notes and broadcasting on the BBC’s musical programmes. He also worked for the London Magazine from 1958 to 1966, latterly as assistant editor.

Meanwhile he was continuing to write and publish poetry, and was praised by a fellow Australian poet, Judith Wright, for his ability to “leave the shape of his experience true and simple”. He quit the stage in the late 50s, his final engagement being in the York Mystery Plays, in which he was Satan, with Judi Dench making her theatre debut as the Virgin Mary – “typecasting” was Osborne’s comment.

His aim was to concentrate on writing and his four studies of major composers, written in a lively style and including musical commentary as well as background material, but aimed at general opera-goers, were well received. These, and the biographies of Auden (with whom he had a special friendship) and Christie, were his most substantial books, but a series of further titles bears testimony to his encyclopedic knowledge: The Opera Lover’s Companion (2007), How to Enjoy Opera (1982), The Bel Canto Operas (1994), The Dictionary of Opera (2000), The Concert Song Companion (1974), The World Theatre of Wagner (1982), Schubert and His Vienna (1985).

From 1986 to 1991 he was chief theatre critic of the Daily Telegraph and also contributed criticism on a wide variety of topics to other leading publications, including Opera magazine, on whose editorial board he sat. With his well-stocked mind, waspish humour and entertaining anecdotes, he was excellent company.

His civil partner, Ken Thomson, whom he met in Australia in 1962, survives him.

• Charles Osborne, writer and arts administrator, born 24 November 1927; died 23 September 2017