Once assessed as ‘a sloth with a low drive to work’, the polite and affectionate black labrador enjoys a successful new career as a therapy dog

Marcus is a very good boy.

He’s a four-year-old, 32kg labrador with lustrous black hair, soulful brown eyes and a bodacious bottom.

He’s sensitive and food-motivated; if given the choice between a distressed person and a tasty treat, he might have a hard time picking.

Oh, and don’t mention guide dog school; it’s a touchy subject.