Black and White Long-Haired Cat Found - not sure if it's lost, though!

Hi there, a couple of weeks ago, there was a fairly large long-haired black and white cat in our garden, that our own cat had alerted us to by yowling at him (he's usually really quiet).  At the time I didn't think anything of it, as it was outside and I was inside and I didn't get a good look at it.  This morning, our cat was again trying to make friends with this cat through our conservatory window and I managed to get a better look at it.  He was drinking from our pond and he seems to have some fairly serious matts in his fur and a slight injury to one side of his mouth, but otherwise looks in reasonable condition and pretty well fed, so I'm wondering if he belongs to someone locally but has just gone on a bit of a wander.  He has no collar, but I haven't had him checked for a microchip.  We live on Pemberton, so he's in the gardens between Pemberton and Warham, toward the Wightman Road end.