In 1932 he studied design and drawing under Napier Waller at the Applied Arts School of the Working Men's College (a precursor of RMIT University).
[1] Around this time he met the journalist, book seller, art critic and leading member of the avant garde scene Harry Tatlock Miller (1913–1989).
He and Miller were regular patrons of Café Petrushka on Little Collins St, where they mingled with fellow members of the artistic and bohemian community, and they had the chance to meet some of the visiting Russian dancers.
He was approached to design Serge Lifar's Icare, but although Sidney Nolan was given the commission,[2] Sainthill's consolation prize was being invited to London with the company.
[1][2] The British Council then sent Sainthill and Miller back to Australia, in charge of a major exhibition of theatre and ballet designs, which opened in Sydney in early 1940.
[4] In 1941 he designed the costumes for a Melbourne production by Gregan McMahon of Jean Giraudoux's Amphitryon 38 and the sets for some of Hélène Kirsova's ballets, A Dream – and a Fairy Tale, Faust, Les Matelots and Vieux Paris.
Harold Hobson called Sainthill's design "a rich, scenic orgy of ropes, sails, ships, bawdy houses and barbaric palaces".
Kenneth Tynan was profoundly impressed, not just with Roberto Gerhard's music but also with Sainthill's set design, which he called "pictorially magnificent, a restless Oriental kaleidoscope …".
He designed over 50 major productions in all, up to four in a year, for directors such as Gielgud, Olivier, Helpmann, Richardson, Noël Coward, Joseph Losey and Wolf Mankowitz.
[1] His final project was the designs for the dream sequence in Anthony Newley's film Can Heironymus Merkin Ever Forget Mercy Humppe and Find True Happiness?.
[1] In 1973, Bryan Robertson wrote and Harry Tatlock Miller edited, a memoir titled simply Loudon Sainthill (Hutchinson & Co Ltd, London, ISBN 9780091187309).
[2] In 2013, the College of Arts and Social Sciences of the Australian National University was awarded a grant of $17,500 to publish the first illustrated book on Loudon Sainthill.