There are many Shady characters who were in the Employ of English Sovereigns or the People who "Advised" the King or Queen Robert Cecil Queen Elizabeth's Spy Master was one such person, who hired people to  work as Servants in the Houses of People that were Deemed to be Traitors who would bring harm to the Queen or Replace the English Monarch with the Scottish Catholic Mary Queen of Scots. Then of course there was the ever looming threat of the Spanish, so a Spy Network was an essential to help Protect and Serve the Queen and to Keep all ills away from her Person.

Another story (unproven) was that Robert Dudley 1st Earl of Leicester who was one of Elizabeth Favourites and a contender for the Queen's hand in Marriage had someone approach Cecil on his behalf to have his First Wife Murdered, so he could be Free to marry the Queen. Dudley's first wife was found dead at the bottom of a Staircase. However such was the scandal surrounding the Death, and the rumours of Dudley's involvement in his wife's Death, it became impossible for him to Marry the Queen. Eighteen Years after his first wife's Death, Dudley married for a second time upon hearing this Elizabeth promptly banished her from Court.

oh wow, this is fascinating! how long until some of this details inspires hollywood to make a money. it explains how queen elizbeth knew so much.

@liampie

Kate Blanchett played Queen Elizabeth and Joseph Fiennes Dudley in the film Elizabeth ,

Helen Mirren and Jeremy Irons played the parts in a TV Series.

Another interesting story is the one between Elizabeth and another of her Favourites 

Robert 2nd Earl of Essex.. But that's for another time.