I'm curious because there is an obvious disdain from many of the characters for people involved in ‘the trades’, yet Mr. Darcy and Mr. Bingley are constantly called away 'on business'. So I'm wondering what lines of business they might have been involved in and/or what was 'respectable' back then?

Details / Examples:

1. The Bingley sisters have an obvious contempt towards Elizebeth Bennett’s Uncle Mr. Gardiner (who had “a very respectable line of trade” and had a warehouse).
2. Before Sir William Lucas was knighted he made a modest fortune in a market town. After being knighted he gained a "disgust" to his business and moved to their new estate.
3. Mr. Darcy has a large estate (estates?) and income of £10,000 a year.
4. Mr. Bingley inherited £100,000 when his father passed away and has an income of £5,000 a year.
5. Mr. Darcy and Mr. Bingley were (fictional) gentleman in the late 1790s.