George III of the United Kingdom was said to have married a Quakeress named Hannah Lightfoot on 17 April 1759, prior to his marriage to Princess Sophia Charlotte of Mecklenburg-Strelitz in 1761. If such a marriage had existed in 1761, then his marriage to Charlotte would have been bigamous and all of George's successors would have been usurpers. But no legal marriage to Lightfoot could have occurred. Hannah Lightfoot was already married to Isaac Axelford in 1753. Lightfoot died in 1759, and therefore could not have produced legitimate children from a marriage in April of 1759. George III's marriage in 1761 to Charlotte would therefore clearly not be bigamous. The marriage was mentioned in the 1866 trial of the daughter of impostress Olivia Wilmot, who claimed to be "Princess Olivia". A forged marriage certificate produced at her trial was impounded in 1866 and studied by the Attorney-General. It is now in the Royal Archives in Windsor Castle.