Fans believed that Tommy died in an ambush when he was being transferred while in witness protection.
He suffered full-body burns in the ambush and was later murdered by Jeremy Cole in hospital.
Meanwhile, Chief Philip Osborne has been in the series since day one.
In the first couple of episodes of season six, he appeared in key archive footage relating to the murder of journalist Gail Vella.
Despite not seeing much of Osborne during the series, the character hasn’t slipped the minds of Line of Duty fans, as some still suspect that he could be ‘H’.
DI Steve Arnott (Martin Compston) also has Osborne under his radar especially after unseen footage emerged of him and journalist Gail before she died.
Is Tommy still alive and has he been working with the Chief Constable?
BBC Breakfast airs daily at 6am on BBC One and Line of Duty airs tonight at 9pm.