Thomas Leighton (Governor)
Sir Thomas Leighton (c. 1530–1610) was an English soldier and politician. He served as the Governor of Guernsey and Jersey from 1570 to 1609. Although the ancestral link still awaits confirmation, there is evidence that Sir Thomas and his wife are common ancestors of the current Duke and Duchess of Cambridge; being 12th great-grandparents of William, and 11th great-grandparents of Catherine, which would make them 12th cousins, once removed.
Sir Thomas was knighted in 1579 during the reigns of Elizabeth I and James I. He was from Feckenham, Worcestershire, England, born to John Leighton of Wattlesborough and Joyce Sutton, daughter of Edward Sutton, 2nd Baron Dudley.
Leighton was unpopular as governor. He developed the defensive capabilities of Castle Cornet, but to do so he imposed heavy taxes on the islanders. In 1588 he was sent as a diplomat to Henry III of France, and then served at the camp at Tilbury in the defensive moves against the Spanish Armada. For some years from 1595 he employed Thomas Cartwright as chaplain.
Leighton married Elizabeth Knollys (cousin once removed of Elizabeth I) in 1578. They had two daughters, Elizabeth and Anne Leighton. Anne married Sir John St. John, 1st Baronet of Lidiard-Tregoze The couple also had one son; the father's namesake Thomas Leighton (born 1584), who married Mary, daughter of Edward la Zouche, 11th Baron Zouche.
- Elston, Laura. "Kate's background is a mixed heritage". Sydney Herald Sun - 7 November 2010. Retrieved 23 May 2015.
According to another possible line, they may be 12th cousins if both descend from Sir Thomas Leighton but that still needs to be confirmed.
- Adolph, Anthony. "THE ANCESTRY OF H.R.H. CATHERINE, DUCHESS OF CAMBRIDGE AND H.R.H. PRINCE GEORGE OF CAMBRIDGE". Copyright © 2014 · All Rights Reserved · Anthony Adolph. Retrieved 23 May 2015.
Princess Catherine’s great great grandmother Harriet Albina Davis was descended from the Davenport family. It has been suggested, but not proved conclusively, that these Davenports descended from the marriage of Henry Davenport of Hollon, Shropshire and Elizabeth Talbot. Elizabeth was descended from Sir Thomas Leighton, Governor of Guernsey and his wife Elizabeth Knollys, who were also ancestors of Princess Diana, and there is a possible descent for the Knollyses from Henry VIII, but again this is far from proven.
- Rayner, Gordon. "'Middle-class' Duchess of Cambridge's relative wore crown and attended George V's coronation". UK Daily Telegraph page 7 - 13 September 2013. Retrieved 23 May 2015.
Her ( Duchess of Cambridge's) father Michael is a descendant of Edward III, and the Duchess is a distant blood relative of her husband through their common ancestor Sir Thomas Leighton, an Elizabethan diplomat
- Ogier, D. M. "Leighton, Thomas". Oxford Dictionary of National Biography (online ed.). Oxford University Press. doi:10.1093/ref:odnb/68015. (Subscription or UK public library membership required.)
- Browning, Charles H. "The Magna Charta Barons and Their American Descendants  (Pedigree L)". Genealogical Publishing Com, 1 Jun 2009 (page 164) - Originally published in 1898. Retrieved 12 August 2015.