Hugh Carlton-Hayes is Adrian Mole's employer in Adrian Mole and the Weapons of Mass Destruction - Adrian refers to him mostly as "Mr. Carlton-Hayes." He owns and runs an antiquarian & secondhand bookshop in Ashby-de-la-Zouche.
Mr. Carlton-Hayes is a refined, cultured and benevolent elderly gentleman who loves literature, pipe tobacco and cream buns. He speaks and writes Arabic in some degree. His exact age is never given; but he claims to have served as in infantryman in World War II, so must be at least 75 when Weapons of Mass Destruction begins, in the year 2002. A passionate expert in his profession, he recommends reading material to a variety of customers and is delighted by the discovery of a vast, unwanted book collection in the home of a recently-deceased old lady.
He is vigorous and assertive for his age, once punching out Sharon Bott's 27-year-old boyfriend Ryan, when the belligerent youth refused to leave the shop and insulted him. He has a long-standing emnity with Michael Flowers, and the two of them have come to blows more than once.
Mr. Carlton-Hayes proves to be a good and understanding employer, and is probably the first to make Adrian work efficiently. Sympathising with Adrian's son Glenn and his Army friend Robbie Stainforth, who find military service in Iraq to be traumatic, he sends them a volume of war poetry - and a set of Arabic flashcards, to help interaction with the locals. He forgives Adrian's ocassional late arrivals and absences due to personal problems, offering advice whenever he can. At the end of Weapons of Mass Destruction, he raises Adrian's salary by £200 per month, hoping that this will help Adrian cope with his debt crisis.
He has a partner named Leslie, for whom he left his previous partner over 30 years ago. Adrian (and the reader) are never told if Leslie is male or female, until The Prostrate Years where it is revealed Leslie is, in fact, a man.
Adrian states that he admires Mr. Carlton-Hayes "more than any person I have ever met." He hopes to continue working with him for many years. However, Hugh becomes increasingly ill, making a couple of trips to hospital, where he stays for a few weeks each time. The bookshop eventually has to close, as they are not making any money. Hugh is now incarcerated in a wheelchair, much like George Mole, and invites Adrian to his house for mince pies, where Adrian finally learns Leslie is a man. They sort through the books from the shop and Adrian is given all the valuable ones by Hugh. This is the last time we hear about him.