Good to learn that '553 is still alive and well! One of the first Bulldogs I flew as a ULAS QFI.
When she was a relatively youthful 16 years old, I delivered her to Cambridge for the VOR/DME/ILS mod. - with a young StopStart in the other seat. Then collected her a few weeks later.
'553 certainly had a long career with ULAS - if I recall correctly there was a lingering stink of tobacco in the cockpit, as wasn't she the usual mount of Uncle Pervy, aka 'Cool Col'?
I wonder whether the 'plastic spastic' Teutors will still be flying when they are 40!