In late 1961 it was recognised that the TSR.2 was unlikely to be in full squadron service before 1968, and Soviet air defences in Eastern Europe were improving rapidly and reducing the probability of a successful strike on certain high value targets by the existing subsonic strike aircraft operated by the RAF. A requirement was therefore drawn up for an interim supersonic nuclear strike aircraft, the requirement stating that an existing aircraft should be utilised if possible to meet an in service date in 1963, with multi-role capability also being sacrificed to meet the in-service date.
Coincidentally the requirement was issued at the same time as the US Navy reassigned its nuclear strike capability to its submarine fleet, leaving the recently developed A-5B Vigilante without a role whilst the USN and Congress wrangled over funding for the RA-5C programme. This funding hiatus had left North American with 18 partially completed A-5B airframes littering their shopfloor with no certainty about an order from the Navy, so the company was glad to be able to sell them to the UK.
To meet the in-service date the aircraft was initially taken virtually 'as is' with American avionics and engines, the only major modification being to fit conventional bomb bay doors to the forward section of the weapons bay, a modification originally offered to the USN but not taken up by that service. This change was carried out due to problems encountered with the linear weapons bay of the A-5A using the rearward ejection of stores, where the ejected store tended to be pulled along by the aircraft's slipstream to the detriment of delivery accuracy. The rearmost third of the weapons bay was converted to fuel tankage, and the arrestor hook was removed to reduce weight.
The Vigilante GR.1 proved a good match to the RAF requirement, with even its name falling in line with the other V-force aircraft and all 18 A-5B airframes originally ordered by the USN were purchased. Though its relatively large wing made for a bumpy ride at low level, especially in typical European weather conditions, this was not seen as an issue as it was envisaged that the aircraft would operate primarily at high altitude. Resplendent in their white anti-flash finish ( until a more muted colour scheme was applied in 1967 ) these aircraft became a familiar sight in their QRA shelters until replaced by the GR.2 in late 1969. Throughout its service only the Red Beard nuclear store was carried by the GR.1/GR.1A, it being felt that adapting the limited number of aircraft to carry other stores would not be cost effective given the intended short term of its service, and would affect its availability in its primary role of nuclear deterrent.
This GR.1 is the aircraft used for weapons release trials, ensuring that the Red Beard nuclear store could be successfully deployed from the modified weapons bay of the RAF aircraft. This particular aircraft was temporarily fitted with pod mounted cameras on the wings and under the fuselage to document events during weapons release, with high-viz markings to aid ground tracking.
Following successful completion of the trials the test equipment was removed and the aircraft was released for squadron service. It retained the high viz markings for most of its service career, being used by the OCU as one of its conversion trainers.
Built from the Airfix kit, with bomb bay and doors scratchbuilt from plasticard, nuclear store 'shape' from the Airfix TSR.2, wing camera pods from a YF-12, underfuselage cameras from the TSR.2.