Sense
Magnetoception (or magnetoreception) is the ability to detect the direction one is facing based on the Earth's magnetic field. Directional awareness is most commonly observed in birds, which rely on their magnetic sense to navigate during migration. It has also been observed in insects such as bees. Cattle make use of magnetoception to align themselves in a north-south direction. Magnetotactic bacteria build miniature magnets inside themselves and use them to determine their orientation relative to the Earth's magnetic field.
Airborne Interception radar
First introduced in March 1941, it was found that the ground reflection created a sort of artificial horizon on the bottom of the display, a surprising side-effect which proved very useful. However, the limited power of the magnetron, about 5 kW, provided range of about , not a great improvement over the Mk. IV. Performance of the system at low altitude was so improved over the Mk. IV that it was decided to make an initial run of 100 units out of what were essentially prototype systems as the Mk. VII, requiring very large amount of aircraft space for the install. Conversions on the Beaufighter began in December 1941.