One example of the Horsley, serial number J8620, was equipped with an Armstrong Siddeley Leopard 14-cylinder twin-row air-cooled radial engine. The Leopard was the most powerful radial engine in the world at the time and in consequence promised much better performance.
Meanwhile, another Horsley, J8612, had been equipped with floats and demonstrated that the aircraft could be operated from the water. The Danish Navy showed interest in these developments and, in 1930, ordered an aircraft type based on the design of the Horsley but equipped with the new engine and able to operate as a floatplane.