Thank you, Cat, Christine and 5-e.
Now I think I have a clearer idea of how the word is used. I met a Parisien in our village yesterday whilst dog walking and we got to talking about this and that (as one does in a small village).
He was dressed only in the briefest pair of swimming trunks but he WAS doing some gardening in what he explained was his mother's house and it WAS extremely hot.
We talked about several subjects and the word "convenable" came up, can't remember now in what context but I used it wrongly as usual. He explained in his best English that it can sometimes refer to someone's behaviour!
Aaarrrggghhh, was it convenable, I mean my talking to a man so scantily clothed in full view of anyone walking past?
N'allez pas trop vite - Proust