Not sure if it's been discussed, I saw something on youtube , apparently behind Buckles chair in his office were some golf clubs, could it indicate him being a "caddy"
There are a lot of similarities between this and series 4 in that the OCG put forward a vulnerable patsy and as things went on Buckles took over the case just as he did in series 1
All I know is every character now has two sides to how it could go , I dont think Steve would be corrupt but his addiction could see him doing something silly , he could be in love with Kate , Kate always seems to be shady so there is every chance she is OCG , and the more Hastings is pushed out after fighting for his job, could see him turn
Its interesting how Mercurio said at times it could be implausible at times , so could Kelly Mcdonald just be a good cop who seems to have a nose for crime , so she felt uneasy with that van and was proved right , she is just an innocent odd person.
All I know even after watching every series twice I still haven't got a clue what's going on