A bit of the history of ZD902:
It was converted to be TIARA in the early '90s as a project at DRA Farnborough. The captain was always the rear seat pilot with the pilot evaluating the systems occupying the front cockpit. To get the experimental displays in the front cockpit quite a few displays and controls were relocated to the rear cockpit including the fuel gauges, hydraulic switches and EPS although the engine start panel and X-drive controls remained in the front. One of the worst aspects in the front was that there were no Aj (nozzle) gauges so you relied on the rear seater to call the nozzles when you selected or cancelled reheat. For the early flying the HUD was not operational so all front seat approaches were flown on the small, non-standard standby instruments on the right instrument panel plus the strip AOA gauge - including practise 67 degree swept wing approaches which were interesting! The HUD was the Smiths 'Z' HUD, an early holographic display that had previously been evaluated at Farnborough in a Jaguar T2 (XX835). The biggest problem with it was that it had a very small headbox so even small head movements away from the reference eye position meant that you could not see the symbology.
Its role was to perform research and development tasks into sensor data fusion. Much of the trials equipment was carried in modified fuel tanks carried on the underfuselage shoulder pylons which resulted in quite a restrictive flight envelope. The radar was a Blue Vixen from the Sea Harrier FA2 although its performance was compromised by having the pitot-static boom mounted on the radome. It was also fitted in the late '90s with an IRST mounted on the nose just in front of one corner of the windscreen.
On 18 October 1994, it was the last military aircraft to be flown from Farnborough when it ceased to be a MoD airfield. It then operated at Boscombe Down until its last flight on 30 November 2011. I cannot recall when or precisely what its last trials project was (an IR sensor I think) but in its final months it was used as a support aircraft, including pilot currency flying, in support of the BVRAAM/Meteor missile trials from Boscombe Down.
It is worth remembering that ZD902 was part of a sizable UK MoD R&D Fleet that operated from one of two dedicated UK MoD R&D airfields (Farnborough and Bedford) but they ceased to fulfill this function just over 21 years ago. The dwindling R&D fleet continued at Boscombe Down until not too many years ago with this being one of its last assets. It was a great privilege to have had the opportunity to work in that world on aircraft such as TIARA.