Elizabeth I was a grandchild of Henry VII through his oldest surviving son. Mary, Queen of Scots (aka Mary I of Scotland) was his great-grandchild through his oldest daughter. So the two were first cousins, once removed. read more
In 1558 Mary Queen of Scots, granddaughter of Henry VIII’s elder sister Margaret, had challenged Elizabeth for the throne of England, but had failed. The Catholics believed that because Elizabeth had been declared illegitimate in 1536, Mary’s challenge to the throne was stronger than Elizabeth’s. read more
Yes Mary Queen of Scots was Elizabeth's first cousin once removed. Mary's grandmother was sister of Elizabeth's father Henry VIII. But they were not first cousins. read more