The person who orchestrated this hit needed Alistair Wilson dead, on that date, so a mistaken identity murder wouldn't have solved their problem. I think they would not have given up if that was their mindset and the right Alistair Wilson would have been killed within a reasonably short timescale, not necessarily in the same set up, OR they would have gone into hiding immediately, which would have been obvious to everyone who knew them and to the police, or come forward to the police to identify who posed this mortal danger to them, exposing the extortion if there was any, and seeking protection. This person wasn't prepared to get their own hands dirty, but the right victim would have known immediately who was behind it and would still be alive with this knowledge. I don't think they would just carry on their daily lives and ignore the danger they were in and I believe police would have investigated this angle, IMO.