 Recently, he played the writer and pioneer of policing, Henry Fielding, in the Channel 4 historical drama series "City of Vice" and Denis Thatcher in 2009's "Margaret".McDiarmid played intelligence chief LeClerc in a 2009 BBC Radio dramatization of John le Carré's "The Looking Glass War".In 2014, he played a leading role as British Foreign Secretary Sir Edward Grey in the BBC television drama "37 Days", which is about the diplomatic crisis preceding the First World War.