On learning his wife has given birth to a son, the Russian Grand Duke wagers the last of the Imperial jewels. Some decades later, the son, played by Marcello Mastroianni, sees them as part of an exhibition at an English museum. When he recovers, he assembles a team of lady burglars to steal them.

Mastroianni should be having a lot of fun, playing his role and all his ancestors, and with the women, including Rita Tushingham, Elaine Taylor, Margaret Blye, Francesca Tu, and the Karlin Triplets. He seems at sea speaking English, with none of the comic charm he typically offers in Italian movies. The pacing seems erratic, as if large swaths have been cut out in an effort to transmute smuttiness into ribaldry.

Perhaps it is the lack of anything in the way of character for any of the performers, save for Miss Tushingham, Nora Nicholson as an elderly Grand Duchess, and David Horne in his last screen appearance, as a bleary-eyed English aristocrat. In any case, it's not much good.

I was very surprised to find out that this British comedy starring Italian heartthrob Marcello Mastroianni never made it to the United States for a theatrical release. It is a bright and entertaining comedy about a broke Russian nobleman who finds out that the family jewels of his impoverished dynasty are now in the British museum. Mastroianni enlist the aid of some of the most beautiful jewel thieves from all over the world (Rita Tushingham, Elaine Taylor, Margaret Blye, Francesca Tu among them), and sets out a lavish plot to steal them back at a display of them where they are being modeled, and the Intrigue illusion up to that is quite amusing.

This is one of many Caper comedies of the 1960's that teachers exotic places and some delightfully campy fashions, and Mastroianni keeps having fantasy flashbacks to Russia before the revolution. The credit sequence explain the history of the family, and is quite funny so the story gets off the minute the film begins. This is a parody of Russian nobility told respectfully which includes an elaborate Russian dance that takes place during the presentation. It's a visual treat as well as a witty one, with a bit of farce added into the caper. As usual Mastroianni is dashing and quite the romantic ladies man, although they manage to keep him under control, particularly in one sequence were a few of the female cat burglars seem to be burglaring him.

It's been a long time since I've seen this film, but I watched it a couple of times back in the eighties and thought it was quite funny. Marcello Mastrioanni plays an aristocratic playboy who's descended from the Romanovs. He thinks the Russian Crown Jewels are rightfully his, so when they arrive in London for a museum display he decides to steal them. He recruits a posse of beautiful girls to help him pull of the heist, including his current girl friend Rita Tusingham. "Diamonds for Breakfast" is fairly typical of the kind of light-hearted comedy-caper film popular in the late 60s and capitalizes on the whole Swinging London mystique with its playboy hero and its bevy of young lovelies. It doesn't have a lot of depth but it's fun.