Boardwalk Empire stars Steve Buscemi and Stephen Graham were among a host of celebrities who attended the launch of Sky Atlantic's HD channel.
Buscemi, who recently scooped a Screen Actors Guild Award for best actor for his role as corrupt politician Nucky Thompson in the award-winning series, said he was particularly fond of the costume.
"The style, the fashion of the time, I thought was really cool and I loved wearing the clothes."
British actor Graham plays Al Capone and says the role has given him a new understanding of the Proibition era gangsters.
"To me, it's the first opportunity where Americans who came from second generation Italians, Spanish and Irish, to have this opportunity to obtain the "American Dream", whether by hook or crook, and Capone's method was by crook".