David Llewellyn Lloyd, 1910 1996, Kettering, Northants, UK, was a specialized rifle maker. In the 1950s to 60s he tried to design a "perfect modern stalking rifle" with a low mounted scope that would never loose zero despite heavy knocks. So he designed this scope Mount and rifle style. He preferred small bore HV cartrridges for deer Stalking. He is said to be the real designer of the .244 H&H Magnum cartridge. Rifles made by him, or at least to his design, were also retailed by H&H and John Wilkes.
His Mounts and scopes are adjustable, though not as easy. Windage adjustment is by the Allan head screws at the rear end. Elevation adjustment is sometimes covered by a solid steel plate screwed on to of scope and mount. So you need several tools to resight some of his rifles.