[8] He was the son of Lieutenant Colonel Henry William Huggins, DSO, MC, DL (1891–1965), an Army officer, and Elizabeth Edith Cadbury (née Butler; 1903–1959), of the confectionery dynasty.

Eventually Brett developed precisely honed diction but was born with rhotacism, a speech impediment that prevented him from pronouncing the "R" sound correctly.

He was trained by Elsie Fogerty at the Central School of Speech and Drama, then based at the Royal Albert Hall[18][19] in London, graduating in 1954, but his father had demanded that he change his name for the sake of family honour, so he took his stage name from the label of his first suit, "Brett & Co."[20] In 1959, while Brett was playing Hamlet, his mother was killed in a car crash in the Welsh mountains.

[23] In 1959, Brett had a singing role as the romantic lead of Archie Forsyth in the West End musical Marigold.

The respected theatre critic Harold Hobson wrote of Brett's portrayal that "the incestuous bed was the centre of his performance".

He played many classical roles on stage, including about a dozen Shakespearean parts at the Old Vic, in New York and four while Brett was a member of the National Theatre Company from 1967 to 1970.

Although Brett sang well, as he later demonstrated when he played Danilo in a BBC Television broadcast of The Merry Widow (Christmas Day 1968), his singing in My Fair Lady was dubbed by Bill Shirley.

Around this time, Brett was considered to replace Sean Connery as James Bond (007), but turned the part down, feeling that playing 007 would harm his career.

[25] Some of his appearances were in classical comedic roles, such as Captain Absolute in a television version of The Rivals (1970) and Bassanio in William Shakespeare's The Merchant of Venice (1970) in a National Theatre Company production directed by Jonathan Miller, which also featured Laurence Olivier (as Shylock) and Joan Plowright (as Portia).

He did, though, appear in a few contemporary guest roles, in a couple of the ITC series such as The Baron (1967) and The Champions (1969), wherein he was cast as swarthy, smooth villains.

Brett also appeared in The Incredible Hulk ("Of Guilt, Models and Murder", 1977) and starred as Maxim in the 1979 adaptation of Daphne du Maurier's Rebecca opposite Joanna David.

The film (not to be confused with the 1996 ITV adaptation starring Alex Kingston) was released nearly a year after Brett's death.

Even though he reportedly feared being typecast, Brett appeared in all 41 episodes of the Granada series, plus two television films alongside David Burke and, latterly, Edward Hardwicke as Doctor Watson.

Jeremy Brett and Edward Hardwicke appeared on stage in 1988 and 1989 in The Secret of Sherlock Holmes directed by Patrick Garland.

[37] One of Brett's dearest possessions on the set was his 77-page "Baker Street File" on everything from Holmes' mannerisms to his eating and drinking habits.

He would hurl himself on the ground just to look for a footprint, "he would leap over the furniture or jump onto the parapet of a bridge with no regard for his personal safety.

[45][46][47] Jeremy Brett received the Légion d'honneur in 1994 for his role of Sherlock Holmes at a celebration marking ten years since the series aired.

[54] In the latter part of 1986, Brett exhibited wild mood swings that alarmed his family and friends, who persuaded him to seek diagnosis and treatment for manic depression, also known as bipolar disorder.

One of the side effects of the lithium tablets was fluid retention; Brett was putting on weight and retaining water.

[citation needed] During his last years, he discussed the illness candidly, encouraging people to recognise its symptoms and seek help.

His heart valves had been scarred by rheumatic fever contracted as a child, and on top of this he had been a heavy smoker throughout his life.

Mel Gussow wrote in an obituary for The New York Times, "Mr. Brett was regarded as the quintessential Holmes: breathtakingly analytical, given to outrageous disguises and the blackest moods and relentless in his enthusiasm for solving the most intricate crimes.

"[61] A memorial tree to the actor was planted on Clapham Common – near where Brett had lived locally for many years prior to his death – on 30 March 2007.