grockle

The origin of the word is uncertain. A derivation has been suggested from the eponymous dragon-like creature in the obsolete The Dandy comic strip "Jimmy and his Grockle", based on an earlier strip, "Jimmy Johnson's Grockle", in The Rover comic in the 1920s, somehow leading to use in the present sense in the movie The System (1964). It is doubtful that the word's use in the West of England goes back farther than that.
Eric Partridge's A Dictionary of Slang and Unconventional English also refers to the film The System but suggests another derivation, that holiday visitors in Torbay were compared to little clowns, and Grock (1880–1959) was a famous clown at the time.
A more straightforward derivation is 'grackle' an old term for the jackdaw, from the Latin graculus. It is apposite when considering large numbers of visitors noisily flocking to their holiday destinations.