Line of Duty has ... It’s morse code, dot dot dot dot." It turns out that H is not an initial but a clue as to who is involved. Arnott continued: "The letter h in morse code is four dots.

Line of Duty enthralled viewers ... tap. It’s Morse code, dot dot dot dot." Breaking down the code, Steve said: 'The letter 'H' in Morse code is four dots. H is not an initial, it’s a clue.

So H stands for “how did they think of that?” Line of Duty season five signed off with the bombshell that its ultimate villain is not one but four people. And because this was a Jed Mercurio ...