The tragedy of Queen Mary’s exile in England is familiar as a story of RivalQueens. The imprisonment imposed by Elizabeth 1 seems caused by Elizabeth’s fear of her cousin. Yet Elizabeth defended her Catholic cousin from protestant critics and refused to take action that could lead to her execution. This resistance was overcome by Francis Walsingham, appointed Elizabeth’s chief advisor in 1573, only to find Elizabeth resisted action against Mary. Walsingham as Elizabeth’s secretary of state had the priority to defend Elizabeth from Catholic rebels. The previous Secretary of State, Lord Burghley, had the same priority and wanted to try Mary as inciting Catholic plots. Elizabeth had no problem with executing opponents - the Duke of Norfolk, was executed in 1572 for wanting to marry the Scots Queen – but Mary was untouchable, though Walsingham discovered plot after plot revealing that Mary was Catholic England’s major threatWhy did Walsingham choose to continue the struggle against the Queens? Why finally did he force Elizabeth to put Mary on trial – being executed in 1587? Mary had always known he was her most skilful enemy. But the way Mary was outmanoeuvered by the Man in Black has not been fully told till now. The key factor is not a struggle against one Queen. Walsingham challenged two. Elizabeth had refused to take the advice of her protestant advisors that Catholic Mary was an intolerable danger, but Walsingham broke her resistance by using brilliant espionage to reveal the Babington plotters. Was this double cross simply to trap the Scottish Queen – or was the aim as much Queen Elizabeth?