Tiddles is a common -- or at least, stereotypical -- name for cats in the UK. It comes from either or both of the words tiddle, meaning to fondle tenderly, or tiddly, meaning very small (or, sometimes, drunk). The original use of Tiddles (with the 'S') seems to have been as a slightly silly surname to give fictional characters, a practice that continued through the 1900s.
The first reference I can find to a cat named Tiddles is in The Little Australian, Or The Fairy Queen by Josephine Fiddes, published in 1882. In this case it was a cutesy name given to a kitten by a young girl, and the overtone of a childish name for a little kitten has remained throughout the years.
However, the second reference in print is in
The Strand magazine, in
1894 (vol. 8), in which a grown tabby cat living on
King's Bench Walk (a street in
Temple,
City of London) is praised for being very polite towards the local pigeons. Indeed, the best known Tiddles' were neither named by children nor most famous as kittens.
There are two particularly famous cats that were named Tiddles. The first was a ship's cat born in the late 1930s or early 1940s, who served aboard the HMS Argus and later the HMS Victorious. He was fairly photogenic, and there is a famous photo of him sitting on the HMS Victorious' aft capstan, where he would play with the bell-rope. He was a fluffy (but dignified) black longhair, and there is a unconfirmed theory that he is one of the reasons that black cats are sometimes thought to be lucky in Great Britain.
More recently, and therefore better known to the modern cat enthusiast, is Tiddles, the Paddington Station cat, (1970–1983). This Tiddles lived in the ladies lavatory of Paddington Station, having been adopted by the restroom attendant. He was quite well known, and was well fed by his admirers, both in person and from treats mailed to him by fans. He was perhaps too well treated, and weighed in at 15 kg (32 pounds).
By the mid-1900s the name was well established and was regularly applied to cats, with the occasional use as a name for small dogs, or as a nickname for small children. Modern Tiddles include Mrs. Slocombe's cat on Are You Being Served?, Tiddles the Tortoise on Peppa Pig (which acts suspiciously like a cat), and numerous guest appearances from Monty Python's Flying Circus to Dirk Gently's Holistic Detective Agency to Discworld... and a recent cameo of Mr. Tiddles as Black Panther's pet, a cat dressed in Captain America-style spandex, inserted into the LEGO Marvel Super Heroes 2 video-game by British video game company Traveller's Tales. Tiddles is slowly becoming the most stereotypical name for cats around the world, and is posed to overtake Mittens and Felix any decade now.