As early as 1939, preliminary investigations were undertaken to see if the Spitfire could be fitted with the new Rolls Royce Griffon. The Griffon was a bulky engine and it seemed unlikely that the installation would be successful. However, Rolls Royce worked hard to reduce the frontal area and rework the camshaft and supercharger drives. When finally mounted in the Spitfire Mk XIV, it would add an additional 3 feet in frontal length. In addition, the Griffon rotated in the opposite direction requiring the pilot to correct in the opposite direction on take-off from the conventional Spitfires. The increased length and horsepower also required a five bladed prop and larger vertical stabilizer. The different firing order gave the Griffon its distinctive bark.
The Mk XIV began life as a modified Spitfire Mk VIII and both the Air Ministry and Supermarine always considered it a Mk 8 conversion ... referring to it as such in the first certificate of design issued in 1943 as type 369 .. the certificate simply read:
“Griffon 61, 65 or 85. This aeroplane, basically Spitfire F Mk VIII production has been modified as indicated. Engine mounting Spitfire Mk. 21 production type. Fuselage Spitfire F VIII production adapted to the F 21 type equipment at frame 5. Special longerons and modified tail end. Main planes Spitfire F VIII with modified cooling system and fitted with standard wing tips. Auw 8,600 lb”
As much as it was an interim design, the Spitfire Mk XIV was the first large scale production of a Griffon powered Spitfire. Early production aircraft had a “C” wing while the balance of Mk XIV production used the “universal” “E” wing. Use of an intercooler required two underwing radiators that were larger than previous Merlin Spitfires. Fuel capacity was increased with the addition of a 13 gallon leading edge fuel tank in each wing. By late 1944, Spitfire XIVs were fitted with an extra 33 gal in a rear fuselage fuel tank, extending the fighter's range to about 850 miles.
One problem which did arise in service was localized skin wrinkling on the wings and fuselage at load attachment points; although Supermarine advised that the Mk XIVs had not been seriously weakened, nor were they on the point of failure, the RAF issued instructions in early 1945 that all F and FR Mk XIVs were to be refitted with clipped wings.
The initial Mk XIV’s used the conventional Malcolm Hood while the later units were produced with a cut-down rear vision canopy. Late in 1944 a number of high-back full-span Mk XIVEs were converted by the Forward Repair Unit to have a single camera fitted, facing to port or starboard; a conversion identical to that used on the FRU-converted FR Mk IXC. To achieve this a new hatch, similar to the radio hatch on the port side, was installed on the starboard side, and both hatches were fitted with camera ports in streamlined blisters. Otherwise this version of the FR Mk XIVE was essentially the same as the standard aircraft. Later, purpose-built conversions, also known as the FR Mk XIVE, had the later cut-down rear fuselage with its tear drop–shaped canopy, port and/or starboard camera ports (without blisters), and an additional rear fuel tank of 34 gallons which extended the Spitfire's range to about 610 miles (980 km) on internal fuel. Because it was used mainly at low altitudes the "production" FR Mk XIVE had clipped wingtips.
In total, 957 Mk XIV’s were built, over 430 of which were FR Mk XIV’s. After the war, second hand Mk XIVs were exported to a number of foreign air forces; 132 went to the Royal Belgian Air Force, 70 went to the Royal Indian Air Force and 30 of its reconnaissance variant went to the Royal Thai Air Force. In the end, the Mk XIV was flown by 37 RAF squadrons, some well into the post-war era. It was the only Griffon powered Spitfire to be used in quantity during WWII.
The Mk XIV was used initially by the Air Defense of Great Britain in anti-V-1 missions, but the type was also used by the 2nd Tactical Air Force in Europe and in the Far East during the closing stages of WWII. It remained in RAF service until 1955.
The first squadron to receive the Mk XIV was no. 610 Squadron, who received their machines in early 1944. This was followed by Nos. 91 and 322 Squadrons in March of that Year. On June 13, Germany began launching V-1’s against London. Defense against the V-1 was anti-aircraft guns , barrage balloons and fighters. Initially the Mk IX’s and Mk XII’s were used to counter the new weapons, but they were soon supplemented by the new Mk XIV. A few of the Mk XIV’s were modified to run on 150 octane fuel, which boosted their top speed to 400 mph. By September, the Mk XIV’s were released from anti-diver operations and Nos. 41, 130, 350, 403 Squadrons began front-line high altitude air defense of Great Britain.
Also in September, Mk XIV’s began arriving in Europe to join the 2nd Tactical Airforce with 130 and 402 Squadrons. At the end of December, two more groups, Nos. 41, 350 and 610 Squadrons arrived. Meanwhile 430 Squadron had begun operations from Holland. During the air operations over Europe, the Spitfire Mk XIV pilots would find themselves in competition with the Tempest V units.