
You may recognize O'Hara from a couple of his previous projects in which he worked with other Tudors' actors like as Donnchadh (King of Ireland) in Tristan+Isolde (in which he starred alongside Henry Cavill and Jamie King) and as Sean Kelly in The Matchmaker (as Maria Doyle Kennedy's brother).
A little background on Henry Howard, Earl of Surrey: He was the son of Thomas Howard, 3rd Duke of Norfolk and that makes him Anne Boleyn's first cousin. Although historically he accompanied Anne and Henry VIII on their trip to France to formally present Anne to Francois I as the future Queen of England, the series The Tudors has not introduced him before now.

As for his friends, after Anne's beheading at the end of season two, we saw no more of poet Thomas Wyatt, played by the adorable Jamie Thomas King even though his life was spared and he was released from the Tower. Surrey was a contemporary of Wyatt and shares with him the title of "Father of the English Sonnet." Surrey's closest friend growing up was Henry Fitzroy, whom Hirst chose to kill-off at a historically inaccurate age in season one.
The Tudors is currently shooting in Ireland.