Elizabeth had Mary held under guard throughout her time in England.
Mary’s presence in England caused problems for Elizabeth. Mary, with Catholic help, might try to seize the English throne but Elizabeth feared that if Mary returned to Scotland, she would make the country a base for French and Catholic activities, which Elizabeth opposed.
With Mary imprisoned, the support of the strong, Protestant and pro-English Lords of Scotland was guaranteed.
While Mary, Queen of Scots, was Elizabeth I’s heir, many Catholics believed that Mary’s right to the English throne was actually stronger than Elizabeth’s.
Elizabeth was suspicious of Mary throughout her reign. While Elizabeth disliked the idea of even considering who might succeed her, Mary knew that she would have to please Elizabeth if she was to take the throne.
However, relations between the two were still difficult for the following reasons: