Blackmail is a 1929 British crime thriller film[2] directed by Alfred Hitchcock and starring Anny Ondra, John Longden, and Cyril Ritchard.

In 2017 a poll of 150 actors, directors, writers, producers and critics for Time Out magazine ranked Blackmail as the 59th best British film ever.

[6] On 26 April 1929, Scotland Yard Detective Frank Webber escorts his girlfriend Alice White to a tea house.

The chase leads to the British Museum, where he clambers onto the domed roof of the Reading Room and slips, crashing through a skylight and falling to his death inside.

The opening 61⁄2 minutes of the sound version are silent, with musical accompaniment, as are numerous shorter scenes later, and the entire final chase sequence is from the silent version with occasional non-synchronized vocal interjections, including Donald Calthrop's last words on the dome of the British Museum's reading room.

Gaumont-British's High Treason, directed by Maurice Elvey was also turned into a sound film mid-way during production.

Much like Blackmail, much of the silent footage in High Treason was maintained and dubbed over for the sound version, with Elvey himself voicing some of the minor characters.

[9] Blackmail, marketed as one of Britain's earliest "all-talkie" feature films, was recorded in the RCA Photophone sound-on-film process.

(The first U.S. all-talking film, Lights of New York, was released in July 1928 by Warner Brothers in their Vitaphone sound-on-disc process.)

[10] Lead actress Anny Ondra was raised in Prague and had a pronounced Czech accent that was felt unsuitable for the film.

Rather than replace her and reshoot her scenes, actress Joan Barry was hired to speak the dialogue off-camera while Ondra lip-synched her lines.

[1] In a public poll, Blackmail was voted the best British film of 1929, largely on the basis of the silent version, which, as mentioned above, was more widely seen.

In the same national UK poll, the best films of their respective years were The Constant Nymph (1928), Rookery Nook (1930), The Middle Watch (1931), and Sunshine Susie (1932).

[7][8] Two future directors worked on this production: Ronald Neame operated the clapperboard and Michael Powell took on-set publicity photographs.