'Line of Duty' looks set to end with a feature-length episode next month.
Vicky McClure, Martin Compston and Adrian Dunbar
The BBC's police drama is due to come to a conclusion on May 5th and it is said that after the thriller's huge popularity, the final episode of the fifth series will run for 90 minutes rather than the usual hour, making it the show's longest-ever ep.
A TV source told The Sun newspaper: "Creating a closing episode which is the same length as some feature films shows just how huge this show has become and how much the corporation values it.
"Jed also felt it was necessary to create a bumper finale to tie up the many loose ends created in this series twisting storylines."
Although the BBC has a history of extending the running time for finales - including series three of 'Line of Duty', and 'Bodyguard' - to 75 minutes, it could still be a bit of a logistical nightmare.
The insider added: "It's going to be a bit of a headache for schedulers as it means moving the news to fit in such a lengthy show on a Sunday night.
"But they're determined to create a nationwide shared moment similar to last year's 'Bodyguard' finale, which had 10.4 million tuning in."
It's thought the finale could draw record viewing figures for the Beeb, with the first three episodes already amassing an audience of between 7.3 million and eight million.
Creator Jed Mercurio says the crime series - which stars the likes of Adrian Dunbar (Superintendent Ted Hastings), Vicky McClure (DI Kate Fleming) and Martin Compston (DS Steve Arnott) - could continue beyond a sixth season, which has already been commissioned.
He recently said: "We're looking forward to a conversation with the BBC once series five has aired ... about whether there is an appetite from fans to have more, or whether there's a feeling the show is coming towards its natural arc.
"That conversation will be very specific, which is whether series six will be the last, or whether the BBC would be prepared to commission a seventh so we can approach series six knowing it's not the last."
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