The future King George III was supposed to have been in love with her as a young girl. However, at the King's wedding, she was one of the bridesmaids. Her family was of the opinion that there would be no peace till Lady Sarah was married herself. With a great effort of will she refused James Hay, 15th Earl of Erroll, "not without tears at seeing so great a man for an hour upon his knees; it really would have been much easier to say yes and get him off the floor again. He was 
known as the mighty Ajax, was an earl and a great bigwig in Scotland, but somehow too old for his age and pompous with it." 
She was still only seventeen when she married Thomas Charles Bunbury, the future 6th Baronet. "Mr. Bunbury is a fortunate man," Henry Fox considered. "Not rich enough, but 'tis a match of her own  making, and happiness don't depend on riches. Her least qualification is her transcendant beauty." Thomas Charles Bunbury was a member of Dr. Johnson's famous literary club, a fashionable figure on the Turf and regarded to be a bit of a fop. However, he concentrated on his 
horses, in 1780, he won the first Derby with his horse Diomede but by then he had lost Sarah. 

In late 1767 she fell in love with Lord William Gordon and became pregnant; her husband aware of the situation, acknowledged the child when it was born in December 1768 but made a sworn deposition that he had not slept with Sarah since January 1768. Six weeks after the baby was born, Lord William Gordon resigned his army commission and they eloped. However, they were bombarded with letters from concerned relatives, pointing out their folly, their wickedness, their 
inadequate finances. Sarah became contrite and melancholy; William began to regret his regiment. Bunbury started expensive divorce proceedings, based on her "criminal connection" with Lord William Gordon. It took until 1776 before the divorce was finalised. 
However, Lord William Gordon started to pursue heiresses. Lady  Sarah then was provided with a home and an income by her family. After some time she met her ex-husband and he considered to marry her again but, five years after the divorce, she became the second wife of the Hon. George Napier and they parented eight children, their three eldest sons becoming well-known generals.
 

Source: Leo van de Pas