[2] Amongst the requirements requested in the specification included the use of a de Havilland Gipsy Six engine, the provision of dual flying controls, instrumentation suitable for blind-flying, doors on either side of the cockpit.

[2] It was fitted with a single-piece windscreen made of moulded Perspex, which the company had only recently pioneered on the Miles Whitney Straight.

According to aviation author Don Brown, the Mentor's design process was relatively straightforward, involving only 630 man weeks within Miles' drawing office.

In comparison to the preceding Nighthawk, the Mentor prototype was determined to possess inferior performance attributes, such as being somewhat slow to respond to the controls.

[4] Only a single Mentor is believed to have survived the Second World War; this aircraft (Serial L4420) was declared to be surplus to requirements and thus sold into the civil sector as G-AHKM during May 1946.