Three seat biplane medium day bomber to Specification 9/24. The fuselage was constructed from steel tube with a fabric and plywood covering. Aluminium alloys were used for elements bearing lower structural loads, such as the outer interplane struts and wing ribs. A small compartment under the cockpit enabled the bomb-aimer to lie prone when using his sight, and also housed the radio. The undercarriage had oleo suspension legs and a tailskid. The three bay, staggered wings had a level central section and dihedral on the outer sections (starting at the engines). The wings and tail all had Boulton and Paul's distinctive square profiles. The engines were mounted on the lower wings at the inner wing strut position, the engine mountings being hinged for ease of maintenance; the nose also hinged allowing access to the back of the cockpit instrument panel and to the radio compartment. The Sidestrand usually had a crew of three: pilot, nose gunner/bomb aimer and a rear gunner. Additionally, a navigator/co-pilot could be accommodated in a small cockpit immediately aft of the pilot's. There were three open gun positions; nose, dorsal and ventral. Armament for each position was a .303 in Lewis gun, the weapon being moved between the two rear positions depending on where each aircraft flew in a formation. Bombs were carried internally in open bays set into the fuselage, bomb-load being limited to 1,050 pounds. Two 425 h.p. Bristol Jupiter VI powerplants.

Initial production version. Essentially identical to P.29 Sidestrand Mk.I but incorporated a prominent Servo tab on the rudder and Frise ailerons to reduce pilot control loads. The elevators horns remained unchanged in production models from the Mk I, but the vertical fin became less angular. Automatic sprung leading-edge slats were added to the top planes to reduce stalling speed.

As Mk.II but with revised bomb aimer location with a large nose window, to Specification 10/29 (originally 25/27). Two 460 h.p. Bristol Jupiter VIII or VIIIF powerplants, fitted with Townend rings.

As Mk.II but with two 555 h.p. Bristol Pegasus I.M.3 powerplants, fitted with Townend rings and driving four bladed propellers.

See Note 1.

Initial designation of the P.75 Overstrand.

Improved P.29 featuring an enclosed cabin and a powered nose turret with .303 in Lewis machine gun, though the dorsal and ventral gun positions remained open, albeit shielded, and each now fitted with its own .303 in Lewis machine gun. Initial prototype conversions were to Specification 29/33, with production to Specification 23/34. The airframe was strengthened considerably in many areas, which facilitated an increased bomb capacity of up to 1,500 lb, up to two 500 lb bombs could be carried in the aircraft's recessed bomb cell in addition to two 250 lb bombs on external carriers. A new levered main undercarriage, complete with larger wheels, was also fitted, while the tailskid of the Sidestrand was replaced by a tailwheel. The wing design was also revised, a noticeable sweepback was added to the outer sections in order to compensate for the aircraft's heavier nose section. Two 580 h.p. Bristol Pegasus II.M.3 powerplants.

P.75 Overstrand Specification
Span	Length	Height	Wing Area	Empty Wt	Max AUW	Cruise Speed	Maximum Speed	Range	Service Ceiling
72 ft	46 ft	15 ft 6 in	980 sq ft	7936 lb	11932 lb		148 mph/ 129 kn	545 mi
21.95 m	14.02 m	4.72 m	91.04 m2	3600 kg	5412 kg		238 km/h	877 km

Developed version of the P.75 featuring a retractable undercarriage, an improved nose turret and a folding transparent hood for the rear gunner, part of a long cockpit canopy that stretched from the pilot's position in front of the wings back to the dorsal gun. Two Bristol Pegasus IV powerplants.