His paternal grandfather, John Andrew Thesiger, was born in Saxony but migrated to England and became secretary to Lord Rockingham.

It was decided that he should leave the navy and study law with a view to practising in the West Indies and eventually managing his property in person.

He joined the home circuit, and soon got into good practice at the Surrey sessions, while he also made a fortunate purchase in buying the right to appear in the old palace court (see Lord Steward).

Another change of fortune, however, awaited him, for a volcano destroyed the family estate, and he was thrown back upon his prospect of a legal practice in the West Indies.

During this period he enjoyed a very large practice at the bar, being instructed in many causes célèbres including the Swynfen will case and Cardinal Newman's criminal prosecution for his libel of Giacinto Achilli.

His eldest son, Frederic, who succeeded to his peerage, earned distinction as a soldier, commanding at the disastrous defeat at Isandlwana, but recovering some of his reputation by his victory at Ulundi.

[6] His daughter, Julia (1833–1904) was married to Sir John Eardley Inglis who commanded the British forces during the Siege of Lucknow in 1857.