President Bush's former spokesman Scott McClellan, will testify this week before a US House committee on the leaking of CIA agent Valerie Plame's identity. McClellan's new book about his three years in the White House expresses deep disquiet about a political culture he describes as based on manipulation, partisan point-scoring and outright deception. Stephen Sackur asks him when his principles kicked in and whatever happened to the famed loyalty of 'Team Bush'.