After the various report summaries.
Should Sir Ian go, either resign or be sacked? I say yes. Why? Not for the shooting, but for the 24 hours afterwards.
Either Sir Ian was in the dark or he knew an innocent man was shot. If the latter, then he should go immediately not really for the fact that he lied at the time, but that he has lied since then. If he was in the dark, then he should also go, as he clearly has created an environment whereby he is not told the honest, if ugly, truth. This can be for many reasons - e.g. his subordinates also did not know, they were too scared or were busy butt-covering themselves first etc etc. I do not want to guess what unpleasantness was the reason writhing beneath Sir Ian in his chain of command, only that corporate culture has one prime source - the chief. If the culture was one of butt-covering, incompetence, cowardace or whatever, then Sir Ian is to blame for allowing such people to remain or to allow a view to form that such behaviour is acceptable. I do not recall him sacking anyone himself, so, if he was indeed unaware, he has not fixed it (if I am wrong and people have been kicked out, then I stand corrected). Two reasons for him to go if he was actually unaware.
The rumour has long existed that Cressida Dick was at fault yet she would be "untouchable". She was responsible on the ground in the room. The mark, IIRC, was made with insufficient evidence or intelligence. Once the mark was made and taken as unequivocal truth, the path was set. I see Cressida Dick as the one responsible for permitting the mark to be accepted.
There has been alot of criticism at the "resignation culture" - i.e. the baying for heads. This is a spectacular inversion - no surprise these days considering it is a classic tool of Sociofacsists. The clamour is that resignations and in extremis, sackings do NOT happen when they should and we have the squalid spectacle of people clinging on to their positions long after they should have resigned. In a way it is not unsurprising - all those perks, fat salary, cars and future pensions and sinecures in some sleepy QANGO somewhere.
Unfortunately for us, many people in office these days, and certainly in most Party apparatus, have long had their "Moral Compass" demagnetised.