Production of the Mark I was postponed and work started on an improved sight. Changes involved incorporating the gyro adjusted reticle into a more standard reflector sight system, a non magnifying optical sight that had been around since 1918. Reflector sights consisting of a 45 degree angle glass beam splitter that sat in front of the pilot and projected an illuminated image of an aiming reticle that appeared to sit out in front of the pilot's field of view at infinity and was perfectly aligned with the plane's guns ("boresighted" with the guns). The sight sat some distance away from the pilot, so it was safer to use and didn't impair the pilot’s field of view. The optical nature of the reflector sight meant it was possible to feed other information into field of view. In the reflector sight version, range was measured by comparing the wingspan of the target seen through the sight to a pre-set number. The pre-set number was selected via a large dial on the front of the sight, and the range was then measured by turning another dial on the aircraft's throttle. This new sight became the Mark II Gyro Sight, which was first tested in late 1943 with production examples becoming available later in the same year. Ferranti built a new factory in the Crewe Toll area of Edinburgh, Scotland to build the sights. This factory would later go on to be the center for Ferranti's long history in radar development.