I've got some questions about the signature of Elizabeth I. Before she became Queen she would sign her name with a little square with looped corners and what could be a capital "P" following her name. This mark is similar to the "R" for Rex in the signatures of Henry VII and Henry VIII. Could it possibly mean Princeps (Princess)? She was an heir to the throne according to the will of her father and this could have been a statement of her rank and legitimacy.
And finally, did Elizabeth ever sign herself "the Quene" as all the other Tudor queens did (except probably her aunts, Margaret of Scotland and Mary of France)?
Update: Thanks to PhD Historian for sending a picture of the signature! I've posted it here: http://www.tudorhistory.org/blogpics/ElizabethP.jpg