Line of Duty finale aired in May and some viewers were left disappointed by the controversial ending. The last episode of season six saw Detective Superintendent Ian Buckells (played by Nigel Boyle) unveiled as the fourth man, also known as H.
His identity was discovered by DC Chloe Bishop (Shalom Brune-Franklin), who had been digging into previous police records with the spelling "definately".
Despite viewers thinking they had finally discovered the identity of H, actor Daniel Mays isn't convinced, and he thinks it could be Marcus Thurlwell, who is played by James Nesbitt.
Marcus - who was briefly mentioned back in the third series - was re-introduced midway through season six as a dodgy detective.
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