Avro's design team received instructions in 1934 to develop a twin-engined coastal patrol aircraft. The team leader, Roy Chadwick also designed the legendary Avro Lancaster, so it's not surprising that the Anson turned out to be, in its own way, just as outstanding.

Developed from the Avro 652, to which it bore a marked resemblance, the Anson was originally powered by two 295hp Cheetah VI engines. These were later uprated to 350, 395 and finally 420hp. The Anson 652A was armed with a single forward-firing machine gun and a further flexible gun mounted in a hand-operated dorsal turret. A small bomb load could be accommodated in the fuselage.

When the Anson went into operation in February 1936 it was the first RAF aircraft to feature retractable undercarriage. Nevertheless its fabric covering and simple systems were already outdated. It was this obsolescence that relegated it to the role of trainer and perversely brought about its enormous success. By the end of production in 1952, over 11,000 had been built. Only the Vickers Wellington was produced in greater numbers.

The retractable undercarriage is worthy of mention. Most people visualise the pilot casually flicking a switch; in the Annie he turns a hand-crank - over 140 times. As a result many pilots chose to fly with the undercarriage extended, preferring the reduced performance and higher fuel consumption to the arm-breaking labour of pulling in those heavy wheels.

The Classic Air Force Anson is a T-21, one of 252 built as a navigation trainer for the RAF. It has a single-seat cockpit without dual controls.

The last Ansons to serve were used by the Royal Afghan Air Force, who withdrew them from service in 1972.