Thanks for all the replies. I wish I'd mentioned 'non-electric' in my spec !
I want to make something that looks like a stock fence - but that can be taken down and rolled up.
In darkest Wiltshire a stock fence is square wire net topped with 2 parallel strands of plain or barbed wire; guessing definitions must vary - as I said, I'm an agricultural illiterate!
Intrigued by robthebob's pignet solution - I need to work out what the posts are though.
I'm visualising a sort of tennis net design:
2 strong end strainer posts (50m apart); then winching tight a 50m wire (or wire rope) between the tops (using a trailer winch fitted to one of the post?) and then 'hanging' a lightly tensioned stock fence from it rather like a tennis net (or pig fence - why do pigs have weaker mesh than sheep?)
I was hoping something like that might exist already - or is the design a doomed idea?