Help me remember the title of a book from the 80's

I'm trying to find out the title and author of a book I read in high school back in 1983 when I was 15, In Sydney Australia.

The book was about a young pre-teen boy who runs away. Can't remember if he left from home or an Orphanage or Boarding school.
He hides out in a lake or river side holiday house that is vacant because it isn't the holiday season. he eats their canned food in the house etc hiding from the local sherif.
There is s dual narrative that follows the boy while also following a Cheetah or Leopard that has escaped from the local Zoo. The Leopard I'm thinking is pregnant and the story follows both of them until their paths cross.
Set in England as best I remember.I could be wrong, I would love to re-read this story as it has stuck with me for so long.

Any help would be appreciated.