Ok, let's see if we can lay this one to rest. Before the development of the wristwatch, a watch was about 2" (5cm) in diameter and was carried in a pocket. Originally, the pocket was in the breeches waistband, and was called a fob pocket; nowadays, it's more likely to be a waistcoat (vest) pocket. The watch was a chain, which stopped it falling out and made it easier to draw the watch from the pocket. "Fob" these days usually refers to an ornament on the chain, but at one time the watch was known as the fob. "Kettle and hob" = "fob", QED.

BTW, "Hob" means a hotplate, from asociation with the Devil and the place with all the flames, in the days when the stove would have a fire inside it.

Steve