Line of Duty series six: Who plays Detective Superintendent Ian Buckells?

*Warning: This article contains spoilers for Line of Duty series six*

Line of Duty unmasked the Fourth Man at the heart of corruption in the police on Sunday, with Detective Superintendent Ian Buckells turning out to be H.

It’s a mystery that’s kept viewers guessing for years, but Ted Hastings (Adrian Dunbar), Kate Fleming (Vicky McClure) and Steve Arnott (Martin Compston) found the guilty man during the final episode of series six.

With everyone from Ted Hastings (Adrian Dunbar) to Philip Osborne (Owen Teale) and Patricia Carmichael (Anna Maxwell Martin) suspected of being the bent copper at the top of the tree, the news will have come as a surprise to some viewers.

But Ian has been a part of Line of Duty since way back in series one, and his presence as one of the senior detectives working in the police gave him the position to work closely with the Organised Crime Group (OCG).

He’s been on the show for nine years, after Chief Superintendent Derek Hilton appointed him SIO in the case of Jackie Laverty’s disappearance.

Here’s everything you need to know about him.

Who plays Ian Buckells in Line of Duty?

Ian has been played by actor Nigel Boyle since 2012. He had a part in series one and lead the investigation into Jackie’s disappearance, but didn’t return again until series four.

He made a reappearance after replacing DCI Roz Huntley (Thandiwe Newton) as SIO on Operation Trapdoor on the recommendation of AC-12.

Between his appearances in series one and four, Ian rose from Detective Inspector to Detective Chief Inspector.

What has Nigel Boyle been in before?

Fans were very pleased to discover a link between Line of Duty and the Inbetweeners earlier this year, after realising that Nigel had a small role as the barman in the first ever episode of the hit comedy back in 2008.

His other credits include Small Axe, Peaky Blinders, Doctors, and Coronation Street.

Who is H in Line of Duty?

Ian confessed to liaising with the Organised Crime Group (OCG) during the latest episode, and even boasted of ‘making mugs’ of Ted and the gang.

Many suspected the likes of The likes of Chief Constable Philip Osborne (Owen Teale), Ted Hastings (Adrian Dunbar) and Patricia Carmichael (Anna Maxwell Martin), and Ian’s reveal will have come as a shock to plenty of viewers.

Line of Duty returns on Sunday at 9pm on BBC One.

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MORE : Line Of Duty season 6 finale: Vicky McClure’s mum warns ‘H’ could be Kate Fleming

MORE : Line Of Duty season 6 finale: Vicky McClure’s mum warns ‘H’ could be Kate Fleming