I don't understand the reference to "amours ... cost him 10,000l". Was this another dalliance? How could a footman have incurred such a debt? More detail needed!

Ah, got it. It was the great Perſonage who incurred the penalty, to the benefit of said young lady. Still, did the young lady remain attached to the footman? We'll need to read the book, obvs.

The phrasing isn’t clear but it’s the employer - the ‘Great Personage’ - who incurred that, I imagine from an adultery suit for bedding another man’s wife. The Duke of Cumberland had been ordered to pay this to Lord Grosvenor in 1769, for example