The nine most significant British-made warplanes of World War II

1. Fairey Swordfish

Obsolete years before the war began; the Swordfish ("Stringbag") nonetheless had many successes including the Taranto raid which crippled the Italian navy, and the (later-fatal) wounding of the Bismarck (illustrated above).

2. Short Sunderland

A vast, beautiful, and beloved flying boat - converted from a pre-war airliner; the Sunderland was the most successful of the British Coastal Command aircraft patrolling against U-Boats, in the early years of the Battle of the Atlantic. 

3. Hawker Hurricane and 4. Supermarine Spitfire

Victors of the Battle of Britain: Hurricanes (background of picture) made up the majority of the fighters; Spitfires (in foreground) were overall the best of the RAF's fighters. 

5. Bristol Beaufighter

The first genuine nightfighter (with on-board radar); the Beaufighter served effectively in multiple roles in literally every British theatre of war from early 1941. 

6. De Haviland Mosquito

The fastest warplane in the skies, when it first emerged; the "Wooden Wonder" was a superb medium bomber, nightfighter, pathfinder, and reconnaissance aircraft; through the middle-war period. 

7. Hawker Typhoon

The first British aircraft to be able to overtake and destroy Focke Wulfe 190 raiders at low altitudes; the Typhoon became the main RAF fighter bomber, ground-attack, infantry-support aircraft in the period up to and around D-Day; and was the first aircraft to deploy rockets effectively.  

8. Avro Lancaster

The best heavy bomber of WWII; famed also for the Dambusters raid. 

9. Hawker Tempest

The best British fighter in the last year of the war, and for several years afterwards* especially in the Fleet Air Arm. By far the most effective aircraft at destroying the V1 "doodlebug" flying bomb.

(Illustrated above, I think the Tempest is supposed to have "flipped over" the V1 with its wing, although this was a rare mode of attack - destruction by cannon fire was usual.) 

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*Of the above; the Tempest was the only aircraft with a significant post-war role, especially re-engined with a Bristol Centaurus radial; and re-named the Hawker Sea Fury (illustrated below) and used by the Fleet Air Arm; where it was one of the last generation of piston-engined fighters, before jets decisively took-over. 

Note: I might supplement this at some point (after further consideration) with a list of the most significant US-made warplanes used by the British in WWII...