After early experience in touring companies he established himself as a character actor and director in the West End.

After directing some fifty plays he resigned the directorship of the Old Vic but continued to appear in the company's productions throughout the rest of his career.

He remained with Benson for five years, and made his London debut at the Lyceum in 1900, playing Sir Thomas Grey in Henry V.[1] Harcourt Williams both co-directed and starred in Rosina Filippi's adaptation of Jane Austen's Pride and Prejudice, in a play called The Bennets at the Royal Court Theatre in a special matinee on 29 March 1901.

One of Williams's most notable parts of this period was General Lee in John Drinkwater's Abraham Lincoln in 1919;[5] he later switched to the role of the Chronicler in the same production.

[5] The biographer Jonathan Croall writes of Williams: A sweet, gentle and trusting man, a conscientious objector during the Great War, he was universally known as Billie, and as a vegetarian lived on Bemax [a wheatgerm healthfood] and bread and cheese.

… Williams was an imaginative producer, with a great feel for Shakespeare's poetry, and a desire to introduce a more psychological interpretation of character.

He was also a man with a mission: to get rid of the mannered "Shakespearean voice", to break down the deliberate style of verse-speaking which made productions over-long and tedious.

Williams celebrated his golden jubilee as an actor while appearing in a long-running production of Shaw's You Never Can Tell described by The Times as "the liveliest show in town".