ROUEN 1957 (1957?):
Flying to intercept a mysterious radar reflection, an unknown French Air Force pilot photographed this craft in March 1954 (1957?) over Rouen with his gun-sight camera. The UFO paced the plane for several minutes before speeding off past the maximum velocity of the French airplane. This UFO appears to be of the same type that appeared in McMinnville, Oregon over the farm of Mr. Paul Trent.
Here are more pictures from France.
The Rouen photo was first published in the July 1957 issue of the Royal Air Force Flying Review, and also in Flying Saucer Review in July, 1957.
See also here for additional information.