Line of Duty bosses used the end credits of the finale episode to pay tribute to one of their crew members who died in a motorbike accident.
Graeme Livingstone died in June 2017 after he was involved in a collision with a car, before filming began for the fifth series.
Earlier on Sunday, May 5, before the BBC police drama drew to a close, Martin Compston, who plays DS Steve Arnott, urged fans to watch until the very end of the programme.
Writing on Twitter he said: "Hey folks hopefully if your jaws are back up from the floor in time, there’s a little something at the very end of the show which means a lot to the whole Line Of Duty family, much appreciated if you could stay tuned for it."
Mr Livingstone, from Bangor, was well-known in the television and film industry in Northern Ireland.
He worked across series three and four of Line of Duty in the props department and was also known for his work on Game of Thrones , Peaky Blinders and another BBC show The Fall.
Martin paid further tribute to Graeme in another tweet following the show's climax alongside a photo of Mr Livingstone and the entire shows crew: "Behind every good cast there’s a phenomenal crew.
"To make this show really is a team effort. One important face missing from that top picture though.
"Graeme Livingstone gone but never forgotten, not just to us but the industry across Northern Ireland."
Vicky McClure, who plays DI Kate Fleming in the show, also added her own tribute. She said: "Huge thank you to the LOD family for making this such a special series!
"And to everyone of you that tuned in!!! Graeme who worked in our props dept will always be in our hearts, we miss him dearly.
"There is no one who writes like @jed_mercurio we are extremely lucky."
More than nine million people tuned in to watch the hotly-anticipated final episode - making it the biggest show of the year so far.
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