The Webley-Fosbery was an early automatic handgun based on a revolver design. The top half of the frame was able to slide back under recoil, recocking the hammer and indexing the next round in the cylinder. They were made commercially in both .38 and .455 calibers, with the .455 version attracting interest from British Army officers.
We will have a more complete entry on the Webley Fosbery coming up, but for now we have a bit of video showing the basic function and history of the piece. Sorry for the rather dark footage; we were limited by our location when we had the chance to handle this pistol.