Line Of Duty star Gregory Piper has said he took cold showers to prepare to film the reservoir scenes in the latest episode of the BBC crime drama.

The actor plays Police Constable Ryan Pilkington in the series, a police officer with a secret history with organised crime groups.

In Sunday’s episode he showed he is still working for the criminals, as he forced a police car off the road and into a reservoir before drowning his colleague and attempting to drown a suspect.

Piper told ITV’s Good Morning Britain: “It was very, very exciting when I got to read it, images that are going through your head of what this could be.

“We filmed it in the middle of November so the water was really cold, so my preparation for that was to try and turn the heat down in the shower, but it was so much fun and everyone really looked after me, so it was such an amazing experience.

“I did have a stunt double and sometimes we swapped, so it wasn’t just one person in the water so much, so there were three stunt doubles for all the characters, and three night shoots, and then we did a shoot in a studio as well, and that was a bit warmer.”

Piper first appeared in the debut series of the hit show when he was 13 years old, and said he had no idea his character would be brought back as an adult.

He said: “It was just this absolute magical land as a kid that I got to visit and call it work, so after that I just thought that was amazing and I hope I get to experience something like that again.

“But never in a million years did I think that Ryan would be coming back, so it was a massive shock.”