He was one of the greatest British actors who, along with Laurence Olivier and John Gielgud, made the transition from theatre to films after the Second World War.

Guinness made his name in six Ealing Comedies, starting in 1949 with both A Run for Your Money and Kind Hearts and Coronets (in which he played nine different characters), going on to lead roles in 1951 with The Man in the White Suit and The Lavender Hill Mob (for which he received his first Academy Award nomination), then in 1955 with The Ladykillers, and culminating in 1957 with Barnacle Bill.

Guinness collaborated six times with director David Lean: as Herbert Pocket in Great Expectations (1946); Fagin in Oliver Twist (1948); Col. Nicholson in The Bridge on the River Kwai (1957), for which he won both the Academy Award for Best Actor and the BAFTA Award for Best Actor; Prince Faisal in Lawrence of Arabia (1962); General Yevgraf Zhivago in Doctor Zhivago (1965); and Professor Godbole in A Passage to India (1984).

[6] From 1875, under English law, when the birth of an illegitimate child was registered, the father's name could be entered on the certificate only if he were present and gave his consent.

[8] Guinness's mother later had a three-year marriage to a Scottish army captain named Stiven, whose behaviour was often erratic or even violent.

[16] At the Old Vic, Guinness worked with many actors and actresses who became his friends and frequent co-stars in the future, including Gielgud, Ralph Richardson, Peggy Ashcroft, Anthony Quayle, and Jack Hawkins.

[19][20][21] Guinness then commanded a Landing Craft Infantry at the Allied invasion of Sicily, and later ferried supplies and agents to the Yugoslav partisans in the eastern Mediterranean theatre.

[23] Guinness returned to the Old Vic in 1946 and stayed until 1948, playing Abel Drugger in Ben Jonson's The Alchemist, the Fool in King Lear opposite Laurence Olivier in the title role, DeGuiche in Cyrano de Bergerac opposite Ralph Richardson in the title role, and finally starring in an Old Vic production as Shakespeare's Richard II.

On 13 July 1953, Guinness spoke the first lines of the first play produced by the festival, Shakespeare's Richard III: "Now is the winter of our discontent/Made glorious summer by this sun of York.

[30] In 1950, he portrayed 19th-century British prime minister Benjamin Disraeli in The Mudlark, which included delivering an uninterrupted seven-minute speech in Parliament.

[31] In 1952, director Ronald Neame cast Guinness in his first romantic lead role, opposite Petula Clark in The Card.

[32] Guinness was idolised by Peter Sellers—who himself became famous for inhabiting a variety of characters in a film—with Sellers's first major film role starring alongside his idol in The Ladykillers.

[33] Guinness's other notable film roles of this period included The Swan (1956) with Grace Kelly, in her penultimate film role; The Horse's Mouth (1958), in which Guinness played the part of drunken painter Gulley Jimson, and for which he also wrote the screenplay, which was nominated for an Academy Award; the lead in Carol Reed's Our Man in Havana (1959); Marcus Aurelius in The Fall of the Roman Empire (1964); Lieutenant General Yevgraf Andreyevich Zhivago in Doctor Zhivago (1965),The Quiller Memorandum (1966); Marley's Ghost in Scrooge (1970); Charles I in Cromwell (1970); Pope Innocent III in Franco Zeffirelli's Brother Sun, Sister Moon (1972); and the title role in Hitler: The Last Ten Days (1973), which he considered his best film performance, though critics disagreed.

Guinness also played the role of Jamessir Bensonmum, the blind butler, in the 1976 Neil Simon film Murder by Death.

After appearing in Lean's Great Expectations and Oliver Twist, he was given a starring role opposite William Holden in The Bridge on the River Kwai.

Despite a difficult and often hostile relationship, Lean, referring to Guinness as "my good luck charm", continued to cast Guinness in character roles in his later films: Arab leader Prince Faisal in Lawrence of Arabia (1962); the title character's half-brother, Bolshevik leader Yevgraf, in Doctor Zhivago and Indian mystic Professor Godbole in A Passage to India.

The battle scenes at the end go on for five minutes too long, I feel, and some of the dialogue is excruciating and much of it is lost in noise, but it remains a vivid experience.

Lucas credited him with inspiring the cast and crew to work harder, saying that Guinness contributed significantly to achieving completion of the filming.

[43] Guinness appeared in the film's sequels The Empire Strikes Back (1980) and Return of the Jedi (1983), as a force ghost apparition to the trilogy's main character Luke Skywalker.

[45][46] Guinness was reluctant to appear on television, but accepted the part of George Smiley in the serialisation of John le Carré's Tinker Tailor Soldier Spy (1979) after meeting the author.

[47] Guinness reprised the role in Smiley's People (1982), and twice won the British Academy Television Award for Best Actor for his portrayal of the character.

In 1985 the Hamburg-based Alfred Toepfer Foundation awarded Guinness its annual Shakespeare Prize in recognition of his life's work.

[62] Another biography suggests: "The rumour is possibly a conflation of stories about Alec's 'cottaging' and the arrest of John Gielgud, in October 1953, in a public lavatory in Chelsea, after dining with the Guinnesses at St. Peter's Square.

His wife, who was of paternal Sephardi Jewish descent,[68] followed suit in 1957 while he was in Ceylon filming The Bridge on the River Kwai, and she informed him only after the event.

[77][78] In 2013 the British Library acquired the personal archive of Guinness consisting of over 900 letters, manuscripts for plays, and 100 volumes of diaries from the late 1930s to his death.

[79] Guinness wrote three volumes of a best-selling autobiography, beginning with Blessings in Disguise in 1985, followed by My Name Escapes Me in 1996, and A Positively Final Appearance in 1999.

For a number of years, British film exhibitors voted Guinness among the most popular stars in Britain at the box office via an annual poll in the Motion Picture Herald.