Sarah Churchill, Duchess of Marlborough
Hanbury was the son of a Welsh ironmaster, John Hanbury, and his second wife, Bridget Ayscough, eldest daughter of Sir Edward Ayscough of Stallingborough and South Kelsey. With his father's marriage to Bridget came a fortune of £10,000 and connections with established political families. His mother was a close friend of Sarah Churchill, Duchess of Marlborough.