Warn That Man is a 1943 British comedy thriller film directed by Lawrence Huntington and starring Gordon Harker, Raymond Lovell and Finlay Currie.

The film was made at Welwyn Studios, with sets designed by the art director Charles Gilbert.

Unfortunately for their plans, the niece of the peer arrives unannounced, along with her RAF pilot fiancé, and two of his new friends, who had rescued him at sea when he was shot down.

The photography throughout the film is clever, and especially so in those parts where Raymond Lovell appears on the screen as the real and bogus Lord Buckley at the same time.

"[3] Picture Show wrote: "If you can swallow the possiblity of the impersonation of the whole household of an English country house by Nazi spies you'll enjoy this hectic melodrama of a plot to kidnap the Prime Minister. ...