More a question out of curiosity here regarding the provision of Trainer versions of combat aircraft. What criteria decides whether a "T2" dual seat / dual control version is required?
Looking back in history, neither the Buccaneer or Sea Vixen had a proper T2 variant whilst the roughly similar vintage Lightning and Harrier did have dedicated trainer versions? OK, the Buccaneer had 1 or 2 twin-seat Hunter's modified with Buccaneer instrument panels to give the same cockpit familiarization - but it would not have handled the same way as the real aircraft types. Similarly I don't believe the F4 Phantom had a full T2 version either?
So how come some aircraft of the 60s and 70s had a dedicated Trainer version provided in the scope but not others? And why has the Typhoon got one but the Tornado didn't?