The Boulton Paul P.90 was a heavy bomber designed to the same specification as the Short Stirling.
The P.90 was a four engined heavy bomber designed to specification B.12/36. It would have been powered by four Rolls Royce Kestral engines. The P.90 and similar Boulton Paul P.91 had an unusual tail turret. This would have been carried behind the tail, with the gunner in a central cabin. Four guns would have been carried, two on each side of the aircraft, carried in pods on the ends of a winglet mounted at the base of the fuselage. The aim was to give the aircraft a very wide range of fire. The P.90 would also have had a twin gun nose turret and retractable ventral turret.
The aircraft also had an unusual bomb bay arrangement, made up of two cylindrical cheek mounted bays, on the sides of the lower front fuselage. Each carried revolving racks that could carry 1,000lb bombs, with a total pay load of 14,000lb.
The main wings were thick, with a straight trailing edge and tapered leading edge. The engines were carried in the front of the wings, in nacelles not much deeper than the wings themselves. The retractable main wheels were near the inner engines. The tail was high mounted, with twin rudders at the ends of the horizontal surface.
The P.90 was estimated to have a top speed of 290mph at 15,000ft, a cruising speed of 248mph and estimated service ceiling of 35,000ft, much better than the low ceiling of the Short Stirling.
The P.90 didn't reach the prototype stage, probably because Boulton Paul were then heavily involved in the Defiant project.