I'm curious as to how the killer knew Wilson would be at home, because the description of Wilson's day suggests many variables with the only certitude being that the children would be put to bed, and I would be wanting certainty that he would be at home, not just a probability. So how does the killer know for sure that Wilson is in the house? But he must know. Well, then, how?
And the murder weapon was discarded down a drain very locally, it not being clear when the gun was discarded or by whom, only that it was discovered by a council worker several days after the murder took place.
We're invited to believe that the killing was in some way money/debt/bank/underworld related, which encourages visions of a fleeing killer quickly dropping the murder weapon down a local drain within minutes of the shooting.
However, it might also suggest a disposal of the weapon being carried out by someone with limited time, no opportunity to leave Nairn and this being done at any time prior to the weapon's discovery but not immediately after the shooting. Much less exciting.
You can't leave Nairn. Why not? Because something in your situation not only keeps you there but also limits your time and opportunity within Nairn. So now we potentially have a killer who resides in Nairn, who knows that Wilson will be at home, who after the killing is unable to leave Nairn and whom is possibly limited to being on foot and so can't go far from home.
In terms of the 7 minutes and mystery envelope, muffled voices and whatever was said between husband and wife, you could be at this for years and get nowhere, given that no useful description of the stranger at the door exists, the envelope has vanished and only one party to the conversation survives. Leaving us with a dying man on a doorstep and nothing else.
Mistaken identity? That is one huge house, frankly. And Wilson can be reasonably exactly described, his picture would probably be easy to find, if you had to find such a picture. This isn't some dim murderous city gang member stupidly killing the wrong person. The house is distinct. So was the victim, by age, appearance and address.
If I was possibly going to kill Wilson, hoping he would be at home, and so forth, I'd want to be very sure that my 7 minutes spent on his doorstep didn't include my filmed by his security cameras. I'd need to be certain that no such cameras were in place. The killer needs to have all of this information.
So the person who pulls the trigger is well informed. They know that they aren't on camera. Well, how? And how does the killer then manage to escape the area, again, without any trace of a vehicle, or any CCTV evidence from anyone, or from the town? Supposedly this killer has to stop to discard the weapon. He must be covered in blood. He's just shot a man at close range. And he just vanishes into thin air. Like he never existed. Just gone. No trace of him before, during or after.
Or the alternative explanation. That the killer was already in Nairn, known to Wilson, knew where he would be and that the shooting wouldn't be captured by any camera. That this is why there is no evidence of a suspicious vehicle or blood covered man dropping a gun down a drain or evidence of his existing.
What we need here is 'who benefits?' and then who did benefit, sufficiently to justify the murder. I have no idea. Otherwise than to surmise that the killer probably lived in Nairn, knew where Wilson would be on the night of the shooting, gained significantly from the death (or expected to), had no love of Wilson, was very well informed on the situation at the house, was unable to leave Nairn and that this was literal, so that the gun had to be disposed of very locally, it being, anyway, a gun obtained locally, possibly not for the purpose of murder at all, given that Nairn seems to have a problem with gun ownership.
All conjecture and surmise of course, but no less incredible than the version of events the police and media put out about the Wilson case.
