B-727 Stick Push
I think that Dan-Air was the only company to fit the stick push on the B-727. This was done on the insistance of Dai Davies, the CAA test pilot, despite the fact that the aircraft had been happily flying all over the world without anyone managing to deep-stall the aircraft in airline service.
It cost the company a fortune, and was quickly removed once Mr Davies retired and he was succeeded by someone less dogmatic.
Thereafter he was always known as "Dai the Push" in Dan-Air.