Don and friends Cyril, Steve and Edwin are bus mechanics at the huge London Transport bus overhaul works in Aldenham, Hertfordshire. During a miserably wet British summer lunch break, Don arrives, having persuaded London Transport to lend him and his friends an AEC Regent III RT double-decker bus. They convert the bus into a holiday caravan, which they drive across continental Europe, intending to reach the South of France. On the way, they are joined by a trio of young women Sandy, Angie and Mimsie, who are a singing group Do-Re-Mi, and change their destination to Athens in Greece, which means passing through Yugoslavia. They are also joined by a runaway singer Barbara pretending to be a boy, herself being pursued by her mother Stella and agent Jerry.
Cliff Richard as Don
Lauri Peters as Barbara
David Kossoff as Magistrate
Ron Moody as Orlando
The Shadows as themselves
Melvyn Hayes as Cyril
Teddy Green - Steve
Jeremy Bulloch Edwin
Una Stubbs as Sandy
Pamela Hart as Angie
Jacqueline Daryl as Mimsie
Madge Ryan as Stella
Lionel Murton as Jerry
Christine Lawson as Annie
Wendy Barry as Shepherdess
Nicholas Phipps as Wrightmore