Development

Gilliat got the idea for making the film from a newspaper article he read shortly before World War II. He decided it would make a "chase thriller" in the style of films he had written for Alfred Hitchcock and Carol Reed, notably The Lady Vanishes and Night Train to Munich.^[4] He found it difficult to do during the war years but reactivated it after the war.^[5]

The fictitious "Vosnian" language was constructed for the film by a linguistics expert, combining Latin and Slavic based elements.^[4]

The star role went to Douglas Fairbanks Jr., who had made a number of British films in the 1930s and was keen to work in the country again. His casting was announced in May 1949.^[6]

Fairbanks later said "We have definitely reached a One World status in pictures. British comedy and character acting do not seem remote to us any more."^[7]

In July it was announced that another Hollywood star would play the female lead but by August, actress Glynis Johns got the role.^[8][9]

Filming

Filming began in August 1949. Although there was some filming done at Isleworth Studios in London, Gilliat wanted to make as much of the film on location. There was eight weeks on location filming, in Trento and the Dolomites. Trento stood in for the fictitious capital. Filming finished by November 1949.^[10][11]

Fairbanks later said filming was difficult as some in Italy thought the film was anti-communist while others said it was pro-communist, and the film unit had to avoid riots.^[12] Gilliat said the filming unions were particularly difficult during the making of this film.^[5]

Critical reception

In The New York Times, Bosley Crowther wrote, "... this picture is just about as lively as they come, and under Mr. Gilliat's direction, it moves like an auto gaining speed ... Beautifully photographed in Italian cities and in the Italian Dolomites, the whole adventure has the eminent advantage of a sparkling Continental atmosphere. And it also has the advantage of good performance by all concerned—by Mr. Fairbanks as the kidnapped surgeon, looking a little like Eugene O'Neill; by Miss Johns, very saucy and explosive, as the music-hall girl; by Jack Hawkins as the Vosnian premier [sic], with an Oxford accent and a Nazi attitude; by Herbert Lom as the Balkan shyster and any number of others in small roles."^[13]

Box office

Trade papers called the film a "notable box office attraction" in British cinemas in 1950.^[14] It was one of five successful movies from London Films that year, the others being The Wooden Horse, The Happiest Days of Your Life, Odette and Seven Days to Noon.^[15]

State Secret was less popular in the US but Fairbanks Jr. said "I thought I did my best work ever; Sidney really kept the pot boiling."^[7]

Gilliat thought the film was "underrated" and suffered from being released so closely after The Third Man. He also felt the film "suffered from Douglas Fairbanks Jnr, you needed a very warm personality and we got rather a cold one. But the picture otherwise came off, the thing was highly profitable, got good notices."^[16]