Hawker Hunter XL603 was constructed by Hawker Aircraft Ltd at it Kingston-upon-Thames factory. It was flown on its first flight by David Lockspeiser on 6th December 1958, and was handed over to the Fleet Air Arm at RNAS Lossiemouth the following month. Following preparation for service, it was issued to RNAS Yeovilton's Heron Flight on 12th February 1959 and coded '950' with a VL shore code applied on the tail fin. It remained at Somerset for the next three years, until it was moved to RNAS Belfast for extensive maintenance in March 1962.
Re-introduced to service in May 1963 with 764NAS (Navy Air Squadron) at RNAS Lossiemouth, XL603 was soon on the move to 759NAS at Brawdy, where it was assigned the fleet number '659'. In November 1964, it was moved to RAF Kemble for storage with 5MU (Maintenance Unit), but its stay was brief, as it was returned to Heron Flight at Yeovilton in May 1965 as '949' originally but was later re-coded '738'. Four years of service with the Unit, interrupted by the occasional re-finish or downtime for maintenance, was ended in August 1969 when it was re-issued to 764NAS as '677'.
On 21st July 1972, XL603 was moved back to Kemble for maintenance and subsequent long-term store.

XL603 was transferred to MoD(PE) (Ministry of Defence Procurement Executive) charge at British Aerospace's (BAe) Brough plant on 30th June 1975. It was to be converted to T.8M specification for the Fleet Air Arm, where it was fitted with the Blue Fox radar as used in the Sea Harrier FRS.1, and also had half of its cockpit modified to that of a Sea Harrier. The aeroplane was operated on radar trials at RAE (Royal Aircraft Establishment) Bedford between October 1978 and April 1981, moving on to BAe's Holme-upon-Spalding Moor airfield the following month.

Its trials work complete, XL603 was issued to 899NAS at Yeovilton, the Sea Harrier training squadron on 8th March 1983. Assigned the fleet number '718', the aeroplane received the 899NAS winged fist emblem on the tail fin by the end of the following summer. It was re-coded during 1984 as '720' and then again during 1988 as '724', and continued in 899NAS service until it was ferried to Hurn for a comprehensive overhaul in 1990. It subsequently retired to Yeovilton in the new dark sea grey colour scheme. It flew for the last time with 899NAS on 25th June 1993, and was placed in open store shortly after, acting as a spares ship for the active FRADU aeroplanes. It was offered for disposal at the November 1994 Sothebys auction.

XL603's civilian life

The aeroplane was hammered down for £2,600 to Clive Forshaw, and it was moved by road to Bruntingthorpe airfield in Leicestershire. The aeroplane was placed on static display and was a popular attraction at the airfield's regular open days given its unusual appearance.

During 1999, XL603 was sold to Global Aviation Inc, based at Tulsa in the USA and was dismantled at Bruntingthorpe and shipped over to its new home by sea during March 2000.
A restoration programme was begun to bring the aeroplane back to flying condition, but little progress was heard and the aeroplane was placed in open store, alongside Hunter GA.11 WV267.
News of a change of ownership surfaced in 2010, when XL603 was advertised for sale by its then owner Jaime Pinto. Although not in flying condition, the airframe was registered on the FAA registry as N419ZS and was complete with an engine fitted.
In the latter part of 2015, the airframe was sold to Shannon Hendricks, owner of the world's only airworthy Fairey Gannet, nicknamed "Janet" - but little has been heard of any progress being made on its planned restoration.

In May 2020, the fuselage was photographed at New Richmond Airport, WI.

- January 2021