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 skies Gavin 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 frame Avspecs
Spitfire 3
Close-up of a Spitfire wing Avspecs
Spitfire 4
Avspecs
Spitfire 5
Working on the body of the plane Avspecs
Spitfire 6
A sneak peek at the Avspecs' Warbird Restoration workshop Avspecs
Spitfire 7
Sanding down a wing Avspecs
Spitfire 8
Fitting casing over the engine of the plane Avspecs
Spitfire 9
A close-up at the tail frame of the Spitfire Avspecs
Spitfire 10
The cockpit of a Spitfire Avspecs
Spitfire 11
Inside the cockpit Avspecs
Spitfire 12
Inside the cockpit Avspecs
Spitfire 13
Fixing the Spitfire's landing gear Avspecs
Spitfire 14
Working on the propeller Avspecs
Spitfire 15
Building parts for the Spitfire Avspecs
Spitfire 16
Painting the Spitfire wing Avspecs
Spitfire 17
The Spitfire starts to come together Avspecs
Spitfire 18
Working on the Spitfire Avspecs
Spitfire 19
Close-up of the Rolls-Royce engine Avspecs
Spitfire 20
Testing out the Spitfire Avspecs
Spitfire 21
Getting there Avspecs
Spitfire 22
Preparing the pilot for take-off Avspecs
Spitfire 23
Off we go! Avspecs
Spitfire 24
The majestic Spitfire flies again Scott Slocum
Spitfire 25
The team behind Avspecs' Warbird Restoration of the Spitfire Avspecs