The Mouse was a three-seat low wing cabin monoplane with a retractable undercarriage – quite an innovation in 1933. Comper hoped it would compete with aircraft being produced by de Havilland and Miles. It had a payload of 600 lbs and a covered passenger compartment and was powered by the most economical and reliable engine of its day. It resembled many low-wing lightplane types of the period but it was the designer’s attention to detail that set it apart from its competitors. It had an unusual mechanism to fold its wings. The outer panels of its wings were attached to the centre-section by vertical pins with folding handles screwed into fittings. The double system of push-pull aileron control rods was so arranged so that the task of wingfolding was easily carried out by one person. The plane was built entirely from wood. It was powered by the de Havilland Gipsy Major aircooled, four cylinder, inverted inline engine.
It made its maiden flight on September 11th from Heston in 1933. It was granted an airworthiness certificate on May 22 1934 and at last was ready for sale. It was entered in the King’s Cup at Hatfield but failed to get through its heats.
By 1934 the Comper company was in distress and no orders for the Mouse were forthcoming, although a number of airframes had been started. It was never sold.