Royal Flash is a 1975 British adventure comedy film based on the second Flashman novel (of the same name, 1970) by George MacDonald Fraser.

Though it received good reviews for its performances and action scenes, Royal Flash had only a limited release in cinemas.

Flashman is forced by Otto von Bismarck to impersonate a Danish prince, who is about to marry a German princess (Britt Ekland).

Bismarck does not wish the Princess to marry a Dane, since this may tilt the balance on the Schleswig-Holstein Question and interfere with his plans for a united Germany.

However, Lester enjoyed the novel and then hired George MacDonald Fraser to adapt The Three Musketeers for two successful films in the early 1970s.

The New York Times said "Mr MacDonald Fraser has considerable narrative skill... most ingeniously plotted and often hilariously funny.

It was perhaps a poor choice of mine to pursue because it was a period film, a comic romp with some serious overtones and a lot of swordplay and it did come after Musketeers which was a well loved piece of subject matter.

"[15] Diabolique magazine argued the film suffered from miscasting in key roles, lack of voice over and for perhaps not being the best introduction to Harry Flashman for cinema audiences.