Mr. Tiddles is the Post Office Cat in Ankh-Morpork. Twenty years old - extremely elderly in cat terms - he is not so much set in his ways, as perpetually moving in a very deep groove ground down over the years.
As no definite news has reached us about any encounter with the Disc's greatest cat-lover, it must be assumed that Mr. Tiddles is still walking his time-honoured beat and sleeping in the intray.
In the Ankh-Morpork Post Office Handbook 2007, it is revealed that Mr Tiddles is the latest in a long line of Post Office cats. The original Mr Tiddles arrived on the 21st Sektober 1635 and was in residence for twenty-three years, in that time accounting for 1,137 rats, 1,563 mice and voles, 212 small birds, and one unfortunate junior postman.
Post Office Regulations demand that all kills made by Mr Tiddles are faithfully recorded, by date, time, and species, in the CatLog. This included Junior postman Trinder.
Yet another classic British childrens' TV animation, this time the genial Postman Pat, who is accompanied on his rounds by his faithful black and white cat Jess, no doubt contrary to many a Post Office regulation...