Conversation so far:
When did Mortimer start writing?
World War II.
What type of works did he write?
He worked for the Crown Film Unit under Laurie Lee, writing scripts for propaganda documentaries.
Did he write any novels?
Charade.
When did he write Charade?
CANNOTANSWER.
Did he write any other novels besides Charade?
Mortimer made his radio debut as a dramatist in 1955 with his adaptation of his own novel Like Men Betrayed for the BBC Light Programme.
How did he adapt it?
play.
Did he do any other plays?
His play A Voyage Round My Father.
When did he write that play?
its first radio broadcast in 1963.
What was the play about?
autobiographical, recounting his experiences as a young barrister and his relationship with his blind father.
Are there any other interesting aspects about this article?
But he made his debut as an original playwright with The Dock Brief.

Question: When did that happen?
Self-contained rewrite: When did John Mortimer make his debut as a playwright?