Line of Duty actor Tommy Gessop has suggested that Ian Buckells' secret identity as 'H' was kept a secret from crew who were not directly involved in the final interview scenes.
The actor, who plays Terry Boyle in the hit cop series, appeared on Good Morning Britain today with his mum after Sunday night's final.
Questioned by hosts Kate Garraway and Sean Fletcher, Tommy said: "I had a feeling who H was..."
Sean asked: "Did you know? Did you guess the right person?"
"We kind of had," he replied. "But Jed [Mercurio] really does keep things top secret until the very last minute."
Asked whether Tommy had told her who he thought H was, his mum Jane said: "No! Well, obviously we had lots of theories over the years. But do we actually know everything even now? I'm still confused! Beautifully confused!"
Sean laughed: "Throwing the cat amongst the pigeons, there! I thought we knew."
Kate also questioned him on whether he had filmed different endings to keep everyone guessing.
"I kind of think we had but some people were quite confused by it all," he replied.
Kate replied: "And that's what we love about it! All the twists and all the turns!"
Tommy also spoke about his dramatic scenes which saw Ryan attempt to murder Terry after driving the police car into the lake.
Thankfully, Ryan wasn't able to murder Terry as DI Kate Fleming had managed to intervene in time.
"I did have a body double when Ryan pushed Terry under water," he told Kate and Sean. "They asked if I was happy to do the big scenes... I really did love filming all of it."
Tommy was also probed on whether it was true he was working with Steven Spielberg, to which he teased: "Possibly!"
*Good Morning Britain airs weekdays at 6am on ITV
