Sellers released his first studio album in 1958 called "The Best of Sellers"; a collection of comic songs and sketches, including Balham, Gateway to the South, where he plays a variety of comic characters. Produced by George Martin and released on Parlophone, the album reached number three in the UK Albums Chart; The same year, Sellers made his first film with John and Roy Boulting in "Carlton-Browne of the F.O.", a comedy in which he played a supporting role for the film's lead, Terry-Thomas. Before the release of that film, the Boultings, along with Sellers and Thomas in the cast, started filming "I'm All Right Jack", which became the highest grossing film at the British box office in 1960. In preparation for his role as Fred Kite, Sellers watched footage of union officials. The role earned him a BAFTA, and the critic for "The Manchester Guardian" believed it was Sellers's best screen performance to date. In between "Carlton-Browne of the F.O." and "I'm All Right Jack", Sellers starred in "The Mouse That Roared", a film in which Jean Seberg also appeared, and was directed by Jack Arnold. He played three distinct leading roles: the elderly Grand Duchess, the ambitious Prime Minister and the innocent and clumsy farm boy selected to lead an invasion of the United States. The film received high praise from critics.