Britain's Prince William and his girlfriend Kate Middleton are reportedly distant cousins.

The royal couple - who have been dating on and off for almost eight years - are related to each other by an Elizabethan soldier named Sir Thomas Leighton.

He is William's 12th generation great-grandparent, and Kate's 11th - meaning the pair are 12th cousins, once removed.

He disregarded civil liberties and kept people down by main force.

The revelation by Britain's Daily Mail newspaper has also uncovered how diplomat Sir Thomas was a murderous despot and dictator who was Governor of Guernsey for 40 years.

A rare account of his life explained how he employed a reign of terror over the community.

It said: "He disregarded civil liberties and kept people down by main force."

He was also a fan of gruesome murdering techniques - including hanging, drawing and quartering - and was so hated by Guernsey residents they defaced the official report of his death in 1610.

But despite their common ancestor, William and Kate have recently moved into their own home together.

While the second in line to the throne trains to become an RAF search and rescue pilot in Anglesey, 28-year-old Kate has moved into a house with the prince in North Wales.

She has also given up her full-time job at her parents' internet party planning company Party Pieces to focus on her relationship, sparking rumours of an impending royal engagement.

An insider revealed: "William will be training for three years and they agreed that Kate should be closer to him. They go out to the shops in Blaenau Ffestiniog for groceries and she's settling in well."