Dateline Diamonds (1965)

Lester Benson (Kenneth Cope) manages one of the biggest rock bands in 1960's Britain, the Small Faces (as themselves). He happens to be an ex-con who wants to return to the crime scene. He summons the help of Major Fairclough (William Lucas) who safe-cracks diamonds to smuggle into the Netherlands via the Big L's ship. It seems a perfect crime as there are no witnesses, except for an intellectually-challenged bus conductress, Mrs. Edgecomb (Patsy Rowlands). Also stars George Mikell.