Watched the first one with the two lads in the flat.
Showed a lovely insight into the ways in which the old bill will change their story to fit to the circumstances. (contains spoilers)
A dog handler is sat in his car, a good 10 storeys below a balcony from which a shot is fired that hits the car windscreen, yet he can describe with accuracy in his statement the person holding the gun. It just happens to be a precise description of the lad who owns the flat, down to the fact that he's bald. Because it's easy to see the top of someone's head when you're 50 feet below them. In a car. With a goosed windscreen.
Then, when the other fella (not bald) confesses to having taken the shot, cut to a room full of his detective colleagues . . . The same colleagues who, just perhaps, had furnished him with the description of the flat owner:
'Well, he'd just been shot at, hadn't he? It'd be easy to get mixed up in those circumstances.'