Contrary to his public persona, Phillips came from a background of poverty. He was born in Tottenham, North London, England, the son of Cecelia Margaret (née Newlove) and Frederick Samuel Phillips, who worked at Glover and Main, manufacturers of cookers in Edmonton, London; the 'filthy, sulphurous' air of the factory gave him a weak heart and dropsy, leading to his death at the age of 44. In 1931, the family moved to Chingford, London where Phillips attended primary school.

It was his mother who decided that Phillips should be sent to the Italia Conti Academy to receive elocution lessons in order to lose his natural cockney accent. At that time a strong regional accent from any city was a major impediment to an aspiring actor. It proved to be an astute move and by the age of 14 Phillips was the family's main breadwinner, saving his mother from squalor.

Phillips made his first film appearances as a child in the 1930s. He is the only actor still alive who performed at Pinewood Studios during the week it opened in 1936. He also understudied for Binkie Beaumont and H.M Tennent in the West End. In 1938, 14-year-old Leslie Phillips appeared with Graeme Muir in the West End play Dear Octopus where Muir was the juvenile lead. During the Second World War shows were frequently interrupted by air-raid sirens and Phillips recalls in his autobiography that 'audiences would evaporate and head for cellars or Underground stations'.

Due to his acquired upper crust accent, Phillips was selected for officer training at Catterick and duly commissioned as a Second Lieutenant in the Royal Artillery in 1943. He was transferred to the Durham Light Infantry in 1944 but was later declared unfit for service after being diagnosed with a neurological condition that caused partial paralysis. He was initially sent to a psychiatric hospital in error but was then sent to the correct facility for treatment.

Demobbed as a Lieutenant in December 1944, Phillips' acting career initially took in 'the murkiest rat-infested old playhouses and music halls in the North of England'. It was during the 1950s that he became known for playing amusing English stereotypes. His distinctive, seductive voice is his trademark as well as his catchphrases, "I say, Ding Dong" (originally the catchphrase of Phillips' character Jack Bell in Carry On Nurse), "Hello" and "Lumme!", which were partly, if not wholly, based on those of fellow cad actor Terry-Thomas. He appeared in three of the early Carry On films series (Carry On Nurse, Carry On Teacher and Carry On Constable) and the 1990s revival Carry On Columbus, as well as several films in the 'Doctor' series. From 1959, Phillips became familiar on radio with a leading role in The Navy Lark.

After his marriage to Angela Scoular in 1982 Phillips decide to move away from the kind of lecherous twits with suave chat-up lines which had characterised much of his previous work. Phillips has remained busy in both stage and television productions, along with character roles in films like Tomb Raider (2001) and Steven Spielberg's Empire of the Sun. Phillips has also recently provided the voice for the Sorting Hat in the Harry Potter films appearing in Harry Potter and the Philosopher's Stone and Harry Potter and the Chamber of Secrets as well as reprising his role for the new attraction, Harry Potter and the Forbidden Journey in Islands of Adventure. He has also appeared in British sitcoms, including Honey for Tea with Felicity Kendal. He has appeared in cameo roles in the police series The Bill.

In 2007 he appeared in Hanif Kureshi's film Venus alongside Peter O'Toole and was nominated for a BAFTA for best supporting actor for his role as the veteran actor, Ian.

Phillips' autobiography, Hello was published by Orion in 2006. ISBN 0-7528-8178-7.

Already an OBE, he was appointed a CBE in the 2008 New Year Honours.

Phillips married his first wife actress Penelope Bartley on 30 May 1948. They had four children, Caroline, Claudia, Andrew and Roger, but by 1960 Phillips' work commitments began to take their toll on the marriage. As he put it in his autobiography: "Penny never objected to the money coming in, but she had begun to complain about my absences."

In 1962 Phillips starred in a play called The Big Killing and was immediately attracted to the understudy Caroline Mortimer, daughter of writer Penelope Mortimer and stepdaughter of Sir John Mortimer. (Before marrying John Mortimer, Penelope had had four daughters by three men). At 19, Caroline was 18 years younger than Phillips however the attraction was mutual. In his autobiography he writes of his dilemma: despite his public image he had been a loyal and faithful husband up to this point and battled with his conscience. Though his wife Penelope had distanced herself from his career and there was a growing distance between them, still he felt torn. However, as the play's run continued he got more deeply involved with Mortimer, eventually meeting her mother.

"I was certain at first that they didn't consider me very suitable ... Penelope Mortimer took a long-nosed view of the kind of light comedy in which I'd had so much success. Perhaps, like many people, she didn't appreciate that from a technical point of view it was often a great deal harder to bring off than straight drama."

Ultimately Phillips was forced out of the family home against his wishes when a friend of his wife conveyed the information of his affair and Bartley decided she wanted a divorce. Phillips was spending more time with Mortimer's family, taking a foreign cruise with them and being a regular guest at the dinner table. As the divorce dragged on, life became difficult for Phillips who was attempting to maintain contact with his children, providing for them and his by now antagonistic wife, and continuing his relationship with Caroline Mortimer, in addition to dealing with the demands of his career. To compound the situation, the same friend who informed Bartley of his affair (and of whom Phillips has expressed his dislike) contrived to have his beloved dog Pippa put down. However, his contact with John Mortimer did at least result in him playing a judge in two of his television dramas. It was truly a turbulent time for the actor as he neared 40. There was respite in happiness at least, as he and Caroline found the then unspoiled island of Ibiza and bought a farmhouse there which played host over the years to Diana Rigg, Nigel Davenport, Laurence Olivier and Denholm Elliott amongst others. While there Mortimer embraced the hippy life and would drift around barefoot, wearing kaftans and bandanas. Although Phillips writes that he was deeply in love with her, by her mid-twenties she was expressing a desire to get married and have children. He cites his reluctance to do either as the cause of the demise of the relationship.

En route to his next job in Australia he was even more baleful when the inflight movie starred no other than Caroline Mortimer. However he soon embarked on a relationship with his co-star Vicki Luke, attracted to her by her sexual energy, attractiveness and unpredictability. After she turned up unannounced on his doorstep in Ibiza, the two embarked on a relationship characterised by risk-taking mainly on her part and which, despite the danger, Phillips found himself drawn to. (There was one instance when, returning from Bangkok, Luke revealed that she had smuggled drugs in Phillips' suitcase).

When he accepted a lead role in the play Sextet in London, he was immediately drawn to his co-star (over whom he had casting approval) actress Angela Scoular, a former Bond girl. Scoular and Phillips began living together at his house in Maida Vale. Around the same time Penelope Bartley had a stroke which left her seriously debilitated. Phillips and Scoular helped her over the years as she struggled with her condition. Phillips has admitted that due to the time they'd spent together he still felt partly married to Bartley. In 1981 he and Scoular left on a tour of a Ray Cooney play in Australia. While there, his daughter Caroline phoned to say that Bartley had died in a fire. Phillips decided to stay in the production as his departure would have meant its closure, so that he didn't return to Britain until 1982. Although the first thing he did was to visit his ex-wife's grave in Horley, Surrey, he has acknowledged that his family has never forgiven him for not coming back to attend the funeral.

In 1982 Phillips and Scoular, 22 years his junior, were married, and remain together. He has admitted that he has never lost his appreciation for a well-made female figure

Phillips has been a lifelong fan of Tottenham Hotspur F.C. and even makes mention of the fact in his 2006 Autobiography Hello:

"I was born in Tottenham just before the team scored a goal and they said my scream was louder than those in the ground. I supported Tottenham Hotspur and have done until this day".

Phillps starred in three early Carry On films, Carry On Nurse, Carry On Teacher, and Carry On Constable. After Carry On Constable he told Carry On producer Peter Rogers that he did not wish to do any more Carry Ons, though he did return for Carry On Columbus in 1992 in the role of a King playing alongside June Whitfield as the Queen in a small cameo role.

Radio

• The Navy Lark
• The Embassy Lark
• Oh, Get On with It! (with Kenneth Williams)
• The Hitchhiker's Guide to the Galaxy as Hactar
• Drop Me Here...Darling
• The Skivers
• The House of Unspeakable Secrets

Television

• Comedy Playhouse: The Time and Motion Man (BBC 29 July 1965)
• The Comic Strip'
• Casanova '73 (BBC, 1973)
• Chancer (Central Television: 1990—91)
• Honey for Tea, (1994)
• Love on a Branch Line, (1994)
• Midsomer Murders, (2004)
• The Catherine Tate Show, (2006)
• Loose Women, (2008)
• Alan Carr's Celebrity Ding Dong, (2008)

Films

• Train of Events (1949)
• Pool of London (1951)
• The Galloping Major (1951)
• The Sound Barrier (1952)
• The Limping Man (1953)
• The Fake (1953)
• As Long as They're Happy (1955)
• Value for Money (1955)
• The Gamma People (1956)
• The Big Money (1956)
• Brothers in Law (1957)
• Les Girls (1957)
• The Smallest Show on Earth (1957)
• The Barretts of Wimpole Street (1957)
• High Flight (1957)
• Just My Luck (1957)
• I Was Monty's Double (1958)
• Carry on Nurse (1959)
• The Angry Hills (1959)
• Carry on Teacher (1959)
• The Man Who Liked Funerals (1959)
• The Navy Lark (1959)
• Night We Dropped a Clanger (1959)
• This Other Eden (1959)
• Ferdinando I, re di Napoli (1959)
• Carry on Constable (1960)
• Doctor in Love (1960)
• Inn for Trouble (1960)
• No Kidding (1960)
• Please Turn Over (1960)
• In the Doghouse (1961)
• Raising the Wind (1961)
• Watch Your Stern (1961)
• A Weekend with Lulu (1961)
• Very Important Person (1961)
• The Longest Day (1962)
• Crooks Anonymous (1962)
• The Fast Lady (1962)
• Father Came Too! (1963)
• You Must Be Joking! (1965)
• Doctor in Clover (1966)
• Maroc 7 (1967)
• Doctor in Trouble (1970)
• Some Will, Some Won't (1970)
• The Magnificent Seven Deadly Sins (Gluttony segment) (1971)
• Not Now, Darling (1972)
• Don't Just Lie There, Say Something! (1973)
• La Mosca Hispanica (Spanish Fly) (1975)
• Not Now, Comrade (1975)
• Out of Africa (1985)
• Monte Carlo (1986)
• Empire of the Sun (1987)
• Scandal (1989)
• Summer's Lease (1989)
• Mountains of the Moon (1990)
• King Ralph (1991)
• Carry on Columbus (1992)
• Bermuda Grace (1993)
• The Changeling (1993)
• The House of Windsor (1994)
• Das Karussell des Todes (1995)
• August (1996)
• Caught in the Act (1996)
• The Canterville Ghost (1996)
• The Jackal (1997)
• Saving Grace (2000)
• Tomb Raider (2001)
• Harry Potter and the Philosopher's Stone (2001) (voice)
• Harry Potter and the Chamber of Secrets (2002) (voice)
• Thunderpants (2002)
• The Hollywood Years (2004)
• Millions (2004)
• Venus (2007)
• Is There Anybody There? (2009)

Video games

Phillips provided his voice for the character of Gex in the UK and European release of Enter the Gecko.