DI Carisle certainly had an oral fixation - here is a list of everything we see him eat throughout the series!
Cup of tea and a breakfast buttie
Welks
Bowl of cereal
Donut
Flake 99(Ice cream cone w/ chocolate stick in it)
Biscuit - I think it's a Jammie Dodger (cookie)
Candy Floss - cotton candy
Cup of tea
Pint of beer
A Drumstick - the candy kind
More Donuts
Cup of tea
Biscuit
Cup of tea
Beer
Heart shaped lolly
Cup of tea
Beer
A chip - fry
He also chews on a pencil and a pen.
He gets a cup of tea in the cafe with Natalie but does not drink it
He pours sugar into a cup of tea when interviewing Mike's fiance but we don't see him drink it
He also rubs his eyes and pulls on his nose a great deal!