Mysterious Beddington Alligator

It was a sunny Sunday, today actually. Jim and Joyce Tucker were making the rounds via boat of Beddington Lake with Carol and Peter Aten. A quick visit to Mike Tobin, to borrow a pair of binoculars turned into a Wild Animal Kingdom moment.
"What's with the alligator on your beach?"
"What alligator?"
Peter and Jim had been chatting, holding the boats for half an hour while the ladies were (naturally) visiting Mike. For some reason, the alligator eluded them. Mike swears he didn't put it there. So the mystery remains...
where did the alligator come from?
And when?

And WHY????