Episode 3 explores how opposition parties prepare for a potential transition of government, with ministers, civil servants and advisers, including Jonathan Powell, Harriet Harman, Gus O’Donnell and Oliver Letwin, revealing how they got ready for the possibility of a change of government.

How does an opposition develop policies that would actually work once they are in office? How can shadow teams ready themselves for taking over departments? What is the role of the chief of staff in these preparations? And what lessons could the approaches of Tony Blair and David Cameron provide for opposition parties preparing for the possibility of being in government?

Veterans of the 1997 and 2010 transitions share their recollections – and their advice for Keir Starmer’s Labour party as a general election approaches.