"633 Squadron" had its world premiere on 4 June 1964 at the Leicester Square Theatre in the West End of London. While critics derided the wooden acting and hackneyed plot, especially the miscast Mirisch Pictures contract star George Chakiris, the aerial scenes were considered spectacular and with Ron Goodwin's music remained the main attraction. Walter Mirisch recalled that the film earned nearly its entire cost of US$1.3 million out of Eady Levy receipts in the UK, making the film practically cost free when Mirisch released the film throughout the world. The great success of the film worldwide led to Mirisch making a series of UK based Oakmont Productions World War II productions shot mostly in the UK.