The Saunders Severn was a three-engined biplane flying boat intended for maritime patrol duties.

The three 490-hp (365 kW) Bristol Jupiter XI radial engines each had their nine uncowled cylinders forward of the wing leading edge, driving two-bladed propellers.

[4] The Severn first flew in July 1930 and began a test programme with the Marine Aircraft Experimental Establishment (MAEE) at Felixstowe in August.

Some of the faults were serious, like the failure of the central engine mounting and multiple cracks that appeared in the hull; others, like the breaking of brackets and the loss of wing inspection flaps were less serious but numerous.

[4] To explore the balance between good air and water performance and behaviour versus the expanding fault list, MAEE decided the Severn should go on a proving flight to the Near East.

This took the Severn and an accompanying Supermarine Southampton 6,530 miles via Port Sudan and included trials on Lake Timsah.

The conclusions were as before: the Severn performed well in the air and on the water, was seaworthy during a storm and returned without corrosion, but suffered from many problems both small and large.

The second category included broken ribs and a servo-rudder kingpost and the conclusion was that this was not a practical aircraft for Service use, so no orders followed.