Line of Duty creator Jed Mercurio says he knew ending 'wouldn't appeal to everyone' Mirror 5 hrs ago Lily Waddell Line Of Duty boss Jed Mercurio spoke out after fans were left disappointed by the ending of season six. Sunday's explosive finale saw AC-12 unravel the secret identity of H or the Fourth Man as the seemingly bumbling officer Ian Buckles. Fireworks were going off on social media when fans complained about the anti-climatic end to the series which also saw Jo Davidson gain witness protection where she lived happily ever after in a beautiful house with a new lover and a dog.