badly needs a miitary adviser!
Given how basic the whole military angle is to this story, I can’t imagine why they didn’t take a bit more trouble to make it militarily believable.
First off: everybody - not just soldiers - knows that Britain is full of sad wannabes trying to pass themselves off as ex-SAS. Soldiers also know that the one thing real ex-SAS men don’t do is go around telling people that’s what they are. So the moment Stephen does that, in real life Chris would have instantly pegged him for a fraud or a fantasist, rather than saying ‘ooh, yes, please let me train with you’. And the writers went on to make it even sillier by giving Chris an uncle who had been in the same SAS unit Stephen was claiming to have served in. In real life, he’d automatically have made use of that; either by checking Stephen out with his uncle before rather than after taking the matter any further, or brightly saying ‘You were? You’ll know my uncle Alan then!’ and waiting to see how Stephen reacted. (I did just that only a few weeks ago, when someone I had just met claimed to have been a Para and fought at Goose Green. I said ‘How interesting! You’ll remember X from your unit, he lives just a few doors along my street!’ and watched him change the subject rapidly.)
And you’d really think they would have got a past or serving soldier to teach young Joe Dempsie to act being shot at like a real soldier, and tell the director what is or isn’t plausible. Even a teenager who’s been in cadets, or a student who has done a couple of terms in the uni OTC, knows that when you’re being sniped at you don’t rush about, wheezing as loudly as a grampus; you control your breathing, slow down, move quietly – and above all, you don’t show yourself above the skyline! The notion that poor panicky, blundering, wheezing Chris was a veteran of Helmand was utterly unbelievable.