"Feathers are used as a symbol of honor" (OED). Mrs. Gardiner relief to be able to tell the truth for her husband, and take away the false mark of honor.

A county in the East Midlands of England. Jane Austen revised Pride and Prejudice, while she stayed in Bakewell, Derbyshire in at year of 1811.

http://www.orchard-gate.com/lambton.htm

"A discourse, usually delivered from a pulpit and based upon a text of Scripture, for the purpose of giving religious instruction or exhortation" (OED).

The buying power of a thousand pounds, is equivalent to the buying power of $87,093 US dollars today.

https://www.uwyo.edu/numimage/currency.htm

"A four-wheeled open carriage, usually drawn by a pair of horses" (OED).