His father had been an usher to the Chamber under King Henry VII and King Henry VIII. He married Catherine Carey, daughter of Mary Boleyn and possibly Henry VIII. He attended on Anne of Cleves when she landed in England and later identified himself with militant Protestantism. His zeal for the new religion impressed both King Edward VI and Princess Elizabeth. However, when Mary Tudor became queen he left England. Princess Elizabeth wrote to him and his wife, looking forward to their safe return. He corresponded with Calvin and enrolled as a student at the University of Basle. Upon the accession of Elizabeth I, he was appointed a Privy Councillor as well as Vice-Chamberlain of the Queen's household, his wife and her sister becoming gentlewomen of the Privy Chamber. In 1559 he found a seat in Parliament through the patronage of Henry Fitzalan, 12th Earl of Arundel. In 1568 when Mary, Queen of Scots, arrived in England, Sir Francis Knollys, as he was by then, was sent north to take her into his custody at Bolton Castle. In 1578 Robert Dudley, Earl of Leicester and favourite of Queen Elizabeth I, secretly married Sir Francis's daughter, Lettice. Sir Francis then forced them to marry a second time with himself as a witness, fearing that Leicester might disavow Lettice just as he had previously disavowed Douglas, Lady Sheffield. However, when Queen Elizabeth I found this out, she forbade Lettice ever again to come to court and even considered imprisoning Leicester in The Tower. 

Source: Leo van de Pas