[2] The screenplay was by Robert Banks Stewart, based on the 1918 Edgar Wallace novel The Man Who Knew.

[3] It is part of the series of Edgar Wallace Mysteries films made at Merton Park Studios from 1960 to 1965.

During the police investigation the company is temporarily controlled by Frank Merril.

The Monthly Film Bulletin wrote: "Unexciting addition to the Edgar Wallace series, with little or no subtlety or originality.

Bernard Lee is adequate as the Inspector, and Graham Leaman makes much of a tiny part as a Yard ballistics expert.