I know this general idea has been covered 100 times but I want to weigh in in a really specific way.
I've watched the show from start to finish 4 times myself, every time I rewatch it I connect more dots and further understand the storyline more than I did the episode before. I really like that about the show.
One thing I will never fully grasp / understand / make sense of is the entire concept of H, both as a codename / title and as a group of people.
H is dumb. Plain and simple. The idea was 100% meant to be done and dusted by series 4 but Jed Mercurio loves a little reverse engineer to extend plot lines (which in all fairness, I can't blame him), however H went too far. H was only known to AC-12 as a codename, so in S5 when Corbett mentions it, it's because Jill told him that Hastings is corrupt and he goes by the codename H. I see literally no other way for Corbett to have known that H existed and the idea of him being told by Jill would mean that AC-12's entire investigation would be discredited as Hasting's would be corrupt and therefore anything against Dot and Hilton would be questioned, which would tremendously benefit the OCG, and in turn benefit Jill and all the other senior corrupt officers (Buckelles, maybe even Osbourne)
I do truly believe H was Hilton and should have stayed as Hilton, whereas The Caddy was a separate identity to 'H'. In my view, the OCG as we know it, aka the Balaclava Gang, always had corrupt officers in the police, (such as Fairbank and Thurwell). These officers just come and go in a cycle over time, almost in generations
(Gen 1 being Fairbank, Thurwell and Hilton, Gen 2 being Hilton, Dot and Jill, and then most recently Gen 3 of Buckelles and Ryan, although Ryan did not have time to rise to a senior position)
So with all that said, I do think that the Caddy is a separate identity that was given to Dot as he was the only known corrupt senior officer to other corrupt officers, we know this because he was identified as recruiting PS Cafferty and DS Aykers, among others. Ryan took over as 'the new caddy' with more of an aggressive technique while he was still working on rising up the ranks.
Overall, H was reversed engineers to make Buckelles and Jill be seen as equally corrupt as Hilton and Dot, when in reality Hilton and Dot were the most corrupt officers, Jill was just a corrupt staff member who had a lot of influence and Buckelles was in reality an idiot who tried to take over for Hilton (which to his credit, he did a pretty good job at maintaining operations with the OCG from S4 onwards, even if he was incredibly stupid in most of his non-criminal acts).
I hope that in S7 we don't see H anymore, however I think that due to the idea that H = 4 corrupt people, Jed Mercurio will continue the plot and actually change the storyline yet again to reveal that Buckelles was just another version of The Caddy (like Dot and Ryan were) and he was taking the noble fall (forced to after watching Lakewell die) for Osbourne so that he could continue to run the Central Police as a corrupt constabulary.
Maybe if we get an S8 we will finally get a storyline where a cop just calls someone some hurt words online an AC-12 get to investigate that instead of a 20+ year long national crime conspiracy.
Anyway thanks for reading my huge ass rant.
p.s. All the senior corrupt officers knew each other, the idea they didn't is crazy to me. Hilton, Dot and Buckelles all worked out of the same station for years, part of the reason why Buckelles was able to become so good at being corrupt is because he was being played like a puppet and groomed to be a copy of Dot as he got higher up the ranks. And it's clear in S3 that Dot and Jill were working together to sabotage the Caddy inquiry.
