Blenheim Mk I
Three-seat twin-engined light bomber, powered by two 840 hp (630 kW) Bristol Mercury VIII radial piston engines, armed with 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.
Company designation 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.
About 200 Blenheim Mk Is were converted into Mk IF night fighters.

Blenheim Mk II
Long-range reconnaissance version with extra fuel tankage.
Only one Blenheim Mk II was built.

Blenheim Mk III
Blenheim Mk IV
Improved version, fitted with protective armour and extended nose, powered by two 905 hp (675 kW) Bristol Mercury XV radial piston engines, 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.

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.
About 60 Blenheim Mk IVs were converted into Mk IVF fighters.

Blenheim Mk V
High-altitude bomber version, powered by two Bristol Mercury XV or XXV radial piston engines.
Blenheim Mk I
Three-seat twin-engined light bomber, powered by two 840 hp (630 kW) Bristol Mercury VIII radial piston engines, armed with 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. Company designation 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. About 200 Blenheim Mk Is were converted into Mk IF night fighters.
Blenheim Mk II
Long-range reconnaissance version with extra fuel tankage. Only one Blenheim Mk II was built.
Blenheim Mk III
Blenheim Mk IV
Improved version, fitted with protective armour and extended nose, powered by two 905 hp (675 kW) Bristol Mercury XV radial piston engines, 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.
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. About 60 Blenheim Mk IVs were converted into Mk IVF fighters.
Blenheim Mk V
High-altitude bomber version, powered by two Bristol Mercury XV or XXV radial piston engines.
Bristol Blenheim