Department of Clarification: Plush shorts and cottons

Loretta reports:

From this society, little Mr. Perker detached himself, on his clerk being announced in a whisper; and repairing to the dining-room, there found Mr. Lowten and Job Trotter looking very dim and shadowy by the light of a kitchen candle, which the gentleman who condescended to appear in plush shorts and cottons for a quarterly stipend, had, with a becoming contempt for the clerk and all things appertaining to 'the office,' placed upon the table.

Being a Nerdy History Girl, I didn’t just shrug and keep reading. I wondered who the contemptuous individual was and what he was wearing. I noted the phrase--incorrectly-- as “plush shorts and stockings.” Then I stuck it in a blog, and aroused the curiosity of one of our Gentle Readers.

Being a NHG, I had to put on my deerstalker’s cap, take out my magnifying glass, and heft the Oxford English Dictionary onto my desk. Here's the result of my detective efforts:

“Shorts” in this case must mean “knee-breeches, small-clothes.”
“Plush” meant the same then as now. The breeches would be plush silk or cotton.
The “and cottons”? Trickier. It could mean flannel (stockings or waistcoat?). But after studying various definitions, I’m gambling on a type of coarse or nappy wool fabric known as “Manchester cottons.”

Since this episode dealt with legal matters, I started out thinking the gentleman was connected to the law courts. There were law messengers called beadles, who wore plush breeches. But the “contempt for the clerk and all things appertaining to ‘the office’" led me to believe this was a footman (technically, not a gentleman), dressed in livery that included plush knee-breeches and perhaps a coarse or nappy wool coat. ???

I wish Norton would make a Critical Edition of The Pickwick Papers, to stop NHGs driving themselves crazy. Meanwhile, if anyone's solved the mystery, please enlighten us.