Episode 4 explores how the governing party prepares for an election while continuing to govern, with ministers, civil servants and special advisers – including Oliver Letwin, Harriet Harman, Gus O'Donnell, Polly Mackenzie and Nick Macpherson – revealing how they approached the work of government during an election campaign.

How does a governing party balance a gruelling campaign alongside running the country? What are the advantages of being the party in power as the election approaches? And how can a governing party make the most of those final months before polling day? Veterans of the 2010 and 2015 elections share their stories.