PTI?
Physical Training Instructor.
Himself was the PTI in Roussillon Barracks Training Camp, Chichester for two years.
The recruits all called him Harry the Bastard. The name stuck for years.
Well. When you scream and shout at peeps who fade and complain and faint in a 16 mile run – you get a bit of a rep.
BTW – This show was banned in my parents house. Along with Fawlty Towers and Monty Python. No wonder I had no idea about prostitutes and all that rampant sexy stuff until I was 20. And got married.