Blenheim Mk.I - Three-seat light bomber, a 0.303 in (7.7 mm) machine gun in the port wing, plus a 0.303 in (7.7 mm) Vickers K gun in the dorsal turret, maximum bombload 1,000 lb (450 kg). 1,552 built. (Type 142M.)
Blenheim Mk.IF - Night fighter version, equipped with an AI Mk III or Mk IV airborne interceptor radar, armed with four 0.303 in (7.7 mm) machine guns in a special gun pack under the fuselage. ~ 200 Blenheim Mk Is were converted into Mk IF night fighters.
Blenheim Mk.IV (Bolinbroke I) - Improved light bomber version, fitted with protective armour and extended nose, armed with a 0.303 in (7.7 mm) machine gun in the port wing, plus two 0.303 in (7.7 mm) machine-guns in a powered operated dorsal turret, and two remotely controlled rearward-firing 0.303 in (7.7 mm) machine guns mounted beneath the nose, maximum bombload 1,000 lb (450 kg) internally and 320 lb (150 kg) externally. 3,307 built. (Type 149)
Blenheim Mk.IVF - Long-range fighter version, armed with four 0.303 in (7.7 mm) machine guns in special gun pack under the fuselage. ~60 Blenheim Mk IVs were converted into Mk IVF fighters.