CMcG, you are right, as usual. Many of us will not need to be THAT dressed up, but then, many of us do not have "Your Grace" or "His Grace" at the beginning of our names. I am betting that people who come out to see a real duke, even one who is selling whisky, would like to see him dressed way way up. And, of course, the same is true for James Bond, or for many bridegrooms.

I remember talking at a function once to a retired USMC colonel, a big man of 6'4" or so. He was wearing a jabot and he described the look he got on his way to the event when he pulled up at a traffic light next to a truck driver. Holding his hand horizontal, as if he was about to pledge allegiance to the flag, he showed me how he winked at the truck driver and flicked his jabot up and out a couple of times.

On the other hand, the jabot worn in the portrait above by Auld Glentruim, in his red waistcoat, is pretty austere, almost like a pair of preaching tabs.