Wow Rob, the cat was very lucky it was not killed by that bloody snake. Theres not a lot you can do to stop it happening again, the snakes are there, just keep any grass around the house cut very short, as usually they prefer long grass, and hopefully now if the cat sees one, it wont want to play with it.
What a shame you are getting rid of the pond. You have done a good job of it, looks good. But, it probably has attracted the snake, if not for the frogs, just for the water.
Maybe you need a dog, that might deter the snakes.
So, whats happening with the shoulder? You having surgery or what?
Give me a call, if you get the time.