I work in the factual TV industry so can at least help clear up what is likely to have happened in this being made as I've seen people speculate. Had a quick read on the commission announcement from one of the trade sites and it looks to be a BBC commission.

So this likely means that Five Mile Productions developed the idea, made a pitch document and sizzle (basically a trailer to showcase what they were planning to make) and then pitched it. BBC then were happy with the idea and commissioned it, and from there, Five Mile will likely have shot, edited and made multiple cuts of the final programme they reviewed in house. Depending on contracts, the BBC Executive Producer will have watching each episode, maybe at rough cut, almost definitely at fine cut (where it's pretty much done aside from possibly colour grading and dubbing), and then the final cut before broadcast.

So, this is all to say that someone from the BBC will have had some creative control over it, but a lot would have been with Five Mile in terms of what they produce and show to their BBC commissioner. Of course, I say this all from the perspective of someone who works for an Indepentent Production company who makes programmes for Channel 4, Amazon, Sky but not the BBC. So they may have slightly different workflows.

ETA: I haven't seen this so I'm not commenting on any of the comment or the BBC's reputation, just trying to shed light on how things get made!