Jacques began her association with the "Carry On" series in March 1958 with the first film in the series, "Carry On Sergeant". She played the small role of Captain Clark, a "battleaxe medical officer" who fails to believe the fabricated ailments of the hypochondriac Private Horace Strong, played by Kenneth Connor. The following year she played "Matron" for the first time in "Carry On Nurse", a film which broke that year's box office records, selling more than 10 million tickets in British cinemas. Although Jacques's role was still relatively small, she appeared in perhaps the best known scene of the film, in which she retrieves a daffodil from Wilfrid Hyde-White's buttocks, put there by a mischievous nurse as revenge for his constant harassment of the staff. So popular was Jacques's scene, that the producers imported two million plastic daffodils from Japan which were then used to promote the comedy. Other characterisations followed, including the formidable maths mistress Grace Short in "Carry On Teacher" (1959) and the friendly Police Sergeant Laura Moon in "Carry On Constable" (1960). Of the former film, Derek Prouse of "The Sunday Times" thought that Jacques "triumph over material so remorselessly juvenile that one is battered into a kind of fascinated admiration".