"God's honest truth, when I was filming Critical [the 2015 Sky series also written by Mercurio] he came in one day and said, 'I've just written a scene where Tony Gates comes back' and I was like, 'Yes, finally'," he told Digital Spy.
"And then he came in the next day and said, 'I read it again and it was rubbish'!"
"That's what he does with people," James added. "So he might do it again, he might not, I don't know. You'll have to ask Jed..."
Interesting. But how would Gates' return have worked? Could the character have survived the accident at the end of series one? Almost certainly not – even Steve Arnott (Martin Compston) couldn't survive stepping into a lorry on a dual carriageway.
Perhaps Gates would have returned in flashback form – but why? If Mercurio brought the idea to James in 2015 or late 2014, he might have been planning the surprise for the show’s third series (airing 2016). The run largely revolved around Dot Cottan, played by Craig Parkinson, finally being exposed as corrupt officer the Caddy.
Did Mercurio imagine Gates returning in old video evidence that would incriminate Cottan? After all, Gates was originally Cottan's boss...
More importantly, could Gates still come back to the show in the future? With his series one sweetheart Jackie Laverty (Gina McKee) making a cameo in series five – well, her corpse, anyway – there’s nothing to stop Gates returning in future.
But in what capacity? Could he expose more bent coppers? The mystery of the fourth and final ‘H’, perhaps?
Not even Ted Hastings himself could crack this case.
Line of Duty will return for a sixth series
