The concept arose immediately after World War I, when the British & Colonial Aeroplane Co. (soon renamed Bristol Aeroplane) began thinking about large transport aircraft powered by steam turbines mounted in an "engine room" in the fuselage and driving wing mounted propellers.
It was recognised that the "engine room" arrangement came with a weight penalty owing to the gearing, clutches, drive shafts and supports, plus the need to strengthen wings but John Dudley North, the Boulton & Paul chief designer argued that the airframe weight would be reduced by 10 per cent due to the all-metal construction, as pioneered in the Boulton Paul P.10.
The Bodmin was a large three bay biplane with unswept and unstaggered square tipped wings of equal span and constant chord.
[3][4] These had leading-edge-balanced ailerons on upper and lower planes and the rather rectangular fin and tailplane carried similarly balanced control surfaces.
Port and starboard airscrews rotated in opposite directions and the fore and aft pairs did likewise, so that either engine could be shut down without any power asymmetry.
The main wide tracked single axle undercarriage had pneumatic springing and damping; a pair of smaller wheels further ahead and closer together served to prevent nose-overs and a standard tail skid extended below the rudder.
The maximum speed and climb rate of the Bodmin were marginally better than those of the identically powered though slightly smaller metal-framed Boulton & Paul Bugle II.