This happened a couple of years ago, but I've just found the video again so thought I'd post it! A bit of background...
The gull had been coming in and stealing my cats' food when they weren't around, which was fine by me as they were on wet food, and you know how that goes in the summer..? So the gull was a waste disposal unit that ate directly out of the cat bowls. I mean, yes, it's a bit odd when you go to make a cup of tea and find that the munching noise from the cat bowls isn't your favourite feline but a wild sea-bird, but never mind...
The gull and his family are still around, they nest on a neighbouring chimney pot every year and continue to provide a useful waste disposal service. They seem quite fond of curry, bacon, ham and, yes, cat food. They will eat fish too! This diet seems entirely successful, as they have not lost a chick, in the four or five years they've been nesting here.
Can't manage to get a link to embed, so you'll have to visit the dreaded Facebook, apologies!
https://www.facebook.com/morrismorrismorrismorrismorris/videos/419070661468484/