In 1615, after Arbella's death, Mary was released from the Tower, partly in recognition of her role in detecting the murder of Sir Thomas Overbury, and partly because her husband was very ill. However, a few years later, in 1618, she was called to give evidence in the course of an inquiry into the rumors that Arbella had secretly given birth to a child. Mary refused to testify, saying she had sworn a binding oath not to, and was returned to the Tower, where she remained until 1623, occupying the best lodgings. Mary was not easily intimidated: Dorothy L. Sayers in her novel "Gaudy Night" described her as "uncontrollable by her menfolk, undaunted by the Tower, and contemptuously silent before the Privy Council". Francis Bacon is said to have remarked that while Lord Shrewsbury was no doubt a great man, there was one greater than he, his wife.