Derelict Cat

We have a new home invader. Near as I can figure, he looks a bit like this. About 2-3 years ago when we finished the ground floor which really acts like a basement because this place is a converted barn, we installed a cat flap for our kitties to use and it has worked well. Our kitties go out and potty or catch mice and come back in through it. However, recently over the past 2-3 weeks, we've been woken at 3am to horrendous cat fights. All unusual for our kitties. And when I've burst out of the bedroom to end the fight, I've caught a glimpse of a large stray tabby. I've been wondering why they've been going through the cat food so quickly. He's getting quite bold more recently as well. I've seen him mid evening chowing down at the cat food on the counter while we've been upstairs watching television. Our cats no longer fight with him either. I've witnessed them just laying about the kitchen with rather confused looks on their little faces while he's eating their chow. Spot, the border collie will chase him off if he catches him. He's very quick and when we show up, he splits down the stairs and out the cat flap. So I wonder who invited him in? Who was he following? This our mysterious, derelict cat.