Ten British folklore and cryptozoology monsters.
The SFX Paranormal Special looks at the topic in Doctor Who as well, noting that there's been at least two explanations for Nessie in the Whoniverse, there are real Yeti and robot Yeti (who occasionally turn up in loos but not often in Northumberland) and the Cottingley Fairies already appeared in the good episode of Torchwood S1.
That still leaves Black Dogs, Alien Big Cats, the Great Grey Man of Ben MacDhui...
To take the last example, what is an insubstantial ghost or shadow creature doing halfway up a bleak Scottish mountain? Is it a psychic echo of where someone died? A living shadow protecting an alien wreck? A warning from the future?