King George V of Britain and Mary of Teck on their wedding day. He was Queen Victoria's grandson, she was of the British royal family and her father was a German Duke. Parents of King Edward VIII and King George VI. Grandparents of Queen Elizabeth II.
Queen Mary, wife of George V, 1914. Mary of Teck (Victoria Mary Augusta Louise Olga Pauline Claudine Agnes; 26 May 1867 – 24 March 1953) was the queen consort of the United Kingdom and the British Dominions, and Empress of India, as the wife of King-Emperor George V.
Probably "Unknown English Lady, school of Larkin" c. 1580 and probably not Mary Queen of Scots. Comparison to the undoubted Mary of Clouet would seem to make the connection doubtful just on the basis of the subject's appearance.