In 1938 John entered L'Ecole des Beaux Arts, Lausanne, where he received the first prize in drawing and design and then went on to the Bartlett School of Architecture, London University, where he took a course in interior decoration. In his spare time he took ballet lessons at the Craske Ryan School while attending evening classes in life drawing and painting under Mark Gertler and Meninsky.He then took a drama course at Everyman's Theatre, Hampstead, and Sir Lewis Casson gave him the part of Marchbanks (a role in which he excelled) in Shaw's Candida, playing opposite Sybil Thorndike at the Old Vic. Casson recognised Leather's abilities, saw that he was dissipating his talents and needed theatrical backbone. He was sent to Elsie Fogerty, the voice expert, and this brought him into the life of the actress Martita Hunt, who took him up and remained a lifelong friend.In 1940 Leather suffered a nervous breakdown, which led to his being confined. During the Second World War (in which he was unfit for service) Hunt secured him Shakespearean parts in repertory and found work for him in Martin Browne's Pilgrim Players and Casson's Theatre Curtain Company.

He played in Sir John Gielgud's last production of Hamlet and in La Folle de Chaillot, with Hunt. But it was Marchbanks that remained his principal character and in the plays of Shaw that he shone. This culminated in a season of Shaw plays produced by Ellen Pollock at the Lyric Theatre, Hammersmith, in 1946.The Forties were John Leather's theatrical apogee. Many who saw him thought he was touched with genius - an opinion not necessarily shared by his fellow actors, who found him an idiosyncratic and unpredictable companion.In 1947, he started his own "Travelling Theatre" of drama, song, music and poetry, a venture that survived for seven years.

Travelling in an old military ambulance without a driving licence (for which he was eventually imprisoned in Exeter Gaol - a period in which he worked in the library and looked back on as a golden time of contemplation), he and a company of two toured the country looking for fit-ups. Patricia Brent, the BBC radio producer, who played on his first tour of Cornwall with John Maxwell, has only memories of incompetence and shambles. His programmes were too rarefied for general taste, houses were seldom good, accommodation hardly ever found.Travelling Theatre took a turn for the better when David Ponsonby, a pupil of Nadia Boulanger, and Hazel Clare joined the company. Patrons were found in Lord Duncannon, Sir Eugen Millington-Drake, Martita Hunt and Esme Percy John Minton made exquisite pen drawings for the programmes. The shows - Alive, Alive O, Skeptic Sceptres and Happy and Glorious - included translations from the lighter French and German writers, English Romantic and humorous playwrights and poets and recitals of early and contemporary keyboard music. Poems of William Plomer and John Betjeman were set to music and performed.

They delighted kindred spirits.In 1954, Harry Leather died and left John an independent income This brought to an end his professional life in the theatre. He bought a small house and lived for a time on Ibiza, in Spain, long before it became a touristic purgatory. In 1956 he had a second nervous breakdown and was again confined. The following year he moved to Primrose Hill and thereafter led a semi-reclusive life broken by long periods in Spain, Italy and Morocco.His house was magically appointed with Empire furniture, mercury-spotted mirrors in gilded frames, lustres, early Staffordshire and Hispano-Mooresque pottery, faded Oriental rugs, books, musical instruments, white walls and dust. It became his private world to which few were admitted.Art came to his rescue as much in Neo-Romantic painting and drawing as in the exercise of aesthetic judgement. He was a critic of acute percipience, and had an almost supernatural affinity with art and music.