I went to college in Cornwall (many years ago), and this is not actually all that uncommon to be honest, although the shark they reported may not be a Great White at all, as there are quite a few varieties of sharks in those waters, and most of them are fairly harmless, even if they are pretty big and scary-looking.
I'd take everything that the Sun reports with a pinch of salt anyway, it thrives on sensationalist nonsense, although it usually does it with a decent amount of humour, sadly, most of which invariably goes right over its average reader's head.
At the end of the day, if someone gets nailed by one swimming around there, tough luck, it's their part of the world, not ours, and they are just 'out earning a crust' as it were.
Chock