The Big Day. (1960 film).

Married 42 year old Victor Partridge is having an assignation with Nina, his 19 year old secretary.

Donald Pleasence as Victor Partridge
Andrée Melly as Nina Wentworth
Colin Gordon as George Baker
Harry H. Corbett as Harry Jackson
William Franklyn as Mr. T. Selkirk
Susan Shaw as Phyllis Selkirk
Molly Urquhart as Mrs. Deeping - Baker's secretary
Betty Marsden as Mabel Jackson
Freda Bamford as Betty Partridge
Marianne Stone as Madge Delaney, Selkirk's secretary
Roddy McMillan as Bob
Timothy Bateson as Clerk
Anthony Bate as Driver
Sabina Franklyn as baby
Derek Briggs as Mechanic

Directed by Peter Graham Scott