I've never heard of Billie Piper until Doctor Who but looking Here she appears to be very popular over seas. Says her leaving was planned the previous year.
Hmmmmm, don't remember her. I'm in the US and don't have BBC3, just BBC America and it's airing "The Unquiet Dead" (an episode I really enjoyed) tonight from Season 1 (refered to as series 1 across the pond).