Martin Compston scares 'Line Of Duty' co-star Vicky McClure with hilarious prank

Watch: Martin Compston shares Line Of Duty pranks with co-star Vicky McClure

Vicky McClure didn't manage to stay as calm as her Line Of Duty character when co-star Martin Compston pulled a prank on her on set.

The actor – who plays DI Kate Fleming in the crime drama – screamed in fright as Compston crept up on her in a video he shared to Instagram.

And Compston – who plays DI Steve Arnott – predicted that Line Of Duty fans might have a similar reaction when the next instalment of the BBC series airs on Sunday.

The actor decided to trick McClure after she’d attempted to pull a similar prank on him – and failed miserably.

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The clip Compston shared shows McClure trying to sneak up on him several times as they hang out on the set of the hit programme.

But he isn’t ruffled at all, and spots her each time.

“FAIL,” the actor captioned his co-star's attempts to prank him in huge red letters, before teasing: “Now it’s Martin’s turn…”

Compston then manages to creep up on McClure undetected and jumps out at her with a loud yell, causing her to scream in panic before she lets rip with a couple of bleeped out words.

“Pranked,” Compston captions the hilarious moment.

The accompanying caption said: “Unflappable when in Arnott mode. @vicky.mcclure still screaming I’m sure.”

“Have a good weekend troops! Line Of Duty 6 Episode 5 Sunday 9pm. Can see a few McClure reactions to the ending.”

Earlier this week, Compston did warn that viewers “will need therapy” by the end of the next episode.

The 36-year-old shared a sneak peek at the instalment on Instagram with the caption: “Episode 5 kicks off as stores reopen and there’s a sale on waistcoats.

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"In all seriousness though if you thought Ep 4 ended on a cliffhanger, you’ll need therapy by the end of Ep 5."