It's the anniversary of the Battle of Britain and we're celebrating the Supermarine Spitfire - the single-seat fighter plane credited with winning against Nazi Germany's Luffwaffe airforce in the first major campaign ever to be fought entirely by air forces.

The Spitfire was hugely popular in many Allied countries during and after WWII, and there were eventually 24 marks of the plane and numerous sub-variants in use up until it was retired in 1955 as new jet engines phased out propeller-powered aircraft.

Spitfire 1
A restored Supermarine Spitfire takes to the skiesGavin Conroy

Today, there are 235 Spitfires remaining across the world, and only 52 of them are airworthy.

A company called Avspecs in New Zealand specialises in restoring vintage and wartime aircraft, making each plane as authentic and accurate as possible, so that it will fly and be as good as a brand new plane straight from a factory. 

Once restored, Spitfires sell for a minimum of £2m ($3.4m) each, while wrecks can be obtained for roughly about £700.

Check out the amazing photographs from Avspecs' award-winning Warbirds Restoration workshop in Auckland, where three different Spitfires, ranging from a mk.5 to a mk.14 are painstakingly being restored. You can read our interview with Avspecs' owner Warren Denholm about restoring Spitfires here

Spitfire 2
Repairing the wing frameAvspecs
Spitfire 3
Close-up of a Spitfire wingAvspecs
Spitfire 4
Avspecs
Spitfire 5
Working on the body of the planeAvspecs
Spitfire 6
A sneak peek at the Avspecs' Warbird Restoration workshopAvspecs
Spitfire 7
Sanding down a wingAvspecs
Spitfire 8
Fitting casing over the engine of the planeAvspecs
Spitfire 9
A close-up at the tail frame of the SpitfireAvspecs
Spitfire 10
The cockpit of a SpitfireAvspecs
Spitfire 11
Inside the cockpitAvspecs
Spitfire 12
Inside the cockpitAvspecs
Spitfire 13
Fixing the Spitfire's landing gearAvspecs
Spitfire 14
Working on the propellerAvspecs
Spitfire 15
Building parts for the SpitfireAvspecs
Spitfire 16
Painting the Spitfire wingAvspecs
Spitfire 17
The Spitfire starts to come togetherAvspecs
Spitfire 18
Working on the SpitfireAvspecs
Spitfire 19
Close-up of the Rolls-Royce engineAvspecs
Spitfire 20
Testing out the SpitfireAvspecs
Spitfire 21
Getting thereAvspecs
Spitfire 22
Preparing the pilot for take-offAvspecs
Spitfire 23
Off we go!Avspecs
Spitfire 24
The majestic Spitfire flies againScott Slocum
Spitfire 25
The team behind Avspecs' Warbird Restoration of the SpitfireAvspecs