The DUP’s most influential behind-the-scenes operator, Johnston was the party’s director of communications before becoming Spad to three Northern Ireland first ministers – Ian Paisley, Peter Robinson and Arlene Foster. Now the party’s chief executive, he was criticised during the renewable heating incentive affair in Northern Ireland, the so-called cash-for-ash scandal. He was crucial to the Conservatives’ deal with the DUP in 2017, negotiating hard for the £1bn the party secured for Northern Ireland as a result. He was first brought to the DUP’s attention when he interviewed then-PM Tony Blair on TV as a schoolboy. With a new leader of the DUP to be elected in the next few days, Johnston’s long reign at the highest level of the DUP could soon be at an end.