Very good.
Finales are always a weak point in this sort of thing, but they kept up the interest AND the believability for pretty much all of it.
He handed a bunch of keys over when he handed over his pass and warrant when he was suspended.Surely Steve doesn't have use of the car as he's suspended? So that should rule him out? Unless he didn't hand in the keys so Dot could claim Steve could've taken it, picked up Denton and shot her.
edit: well I thought he had.
Yes, he definitely handed keys back. Given that most details in this programme matter, I was expecting that to come up at some point, and get Steve sprung. Either it was overlooked, or plod always have a bunch of keys (for lockers-n-stuff), so he kept the car keys.
I'm not commenting on any other plot details, cos my brain is too small to deal with most of them - I prefer the story to be spelt out for me in words of less than 2 syllables
I just sit back and enjoy the acting.