Eyeglasses
You'll notice in John Mortimer's "Opening Remarks" to each episode that he wears very large eyelasses, and has apparently done so most of his life. Interestingly, several characters in various episodes also wear very large eyeglasses, particularly Phyllida Erskine-Brown. Perhaps a little nod to Mortimer's affectation?
"Somewhere along the line the world has lost all of its standards and all of its taste."