Conversation so far:
When did Mortimer start John Mortimer's legal career?
Mortimer was called to the Bar (Inner Temple) in 1948, at the age of 25.
What firm did he work for?
CANNOTANSWER.
What type of law did he practice?
His early career consisted of testamentary and divorce work.
Did that change later in his career?
on taking silk in 1966, he began to undertake work in criminal law.
What is "taking silk"?
CANNOTANSWER.
Did he work on any major cases?
Whitehouse v.
Lemon.

Question: When was this case?
Self-contained rewrite: When was John Mortimer major case about?