I always liked Thurston Howell's lockjaw way of speaking.
It’s NOT the lightly British, New England accent of Dr. Frasier Crane or PBS, but Kelsey Grammer does use it as Sideshow Bob. Although associated with elites, It’s a very bold accent, and most bold accents are working-class. If you think of worlds like “copper” for policeman or “doll” for a girl, you’ll probably hit on it.
Think Hepburn or FDR. Jon Lovitz parodied it as the Master Thespian, but like Kelsey Grammer, he added a little extra Shakespearean accent. Amy Adams put it on in “Night at the Museum.” Also, Carey Grant, William Buckey, George Plimpton, Bette Davis, Princess Leia, Emperor Papatine, James Earl Jones’ Darth Vader,
It was invented to have very strongly enuniciated consonants, particularly of certain consonants that don’t get picked up well over a microphone.
https://www.youtube.com/watch?v=Gpv_IkO_ZBU