When this was first broadcast in the mid-1970's it quickly became one of my Dad's favourites. He had completed his own National Service with the RAF at exactly this time so he could sympathise with the 'erks' and what they endured under Corporal Marsh. He said his introduction to service life was arriving at an RAF station in the pouring rain after travelling from one end of England to the other (taking him at the base nearest to his home would, of course, defy service logic). He was given two damp blankets, and shown to an empty hut - and I mean empty, not even a bed. He lay on the floor in his wet clothes and didn't close an eye all night.
Eventually, after training, he was posted overseas and it is fascinating to look in his photo album and realise these were the dying days of the British Empire: Palestine, South Africa, RAF Khartoum, even Iraq ("Saddam knew my father, father knew Saddam..."). On one occasion he was with a small patrol in the desert. They camped for the night and woke the next morning to find themselves lying on the open sand. Tents, equipment, anything they weren't actually wearing had gone and they never knew a thing. He said they could steal your socks without taking your boots off.
None of this has anything to do with reviewing the programme, but it does show it was grounded in real life. In its day it seemed very funny but nowadays it would be frowned on to call someone 'poofhouse' week after week on prime-time. I don't know why people can't see this as reflecting the ignorance of the person who uses this type of abuse - they insist it makes the show itself 'homophobic'. It was well-written and acted and there are far worse quality programmes around today.