Why was the programme 'last of the summer wine' so called?

Well it's more of a descriptive series name than 'Of Funerals and Fish' - the pilot episode for BBC's Comedy Playhouse (1973).
https://en.wikipedia.org/wiki/Last_of_the_Summer_Wine

Nothing too deep - I think it's meant to portray the three old school friends now retired, going into their second childhood, who wander about their Yorkshire village and surrounding countryside chatting about nothing in particular but still getting into trouble - and acting like naughty boys - last fling at youth, if you like!!