Historically it has been common for Prime Ministers to take on the role of Foreign Minister themselves, particularly if they have an interest in the field. Several New Zealand Prime Ministers including Peter Fraser, Walter Nash, Keith Holyoake, and David Lange held the External Affairs portfolio. The most recent Prime Minister to do this is Helen Clark in 2008 as Acting Minister, and prior to her was Mike Moore, in 1990. Thirteen Prime Ministers have served as Foreign Minister for all or part of their terms.