There are simply too many things which, when added together, make the door handle explanation at the very least incredibly implausible, if not downright impossible:
Firstly, they did not die immediately, or thereabouts, which is what you would expect to have happened had they been contaminated by coming into contact with what was said to be a nerve agent of "high purity".In other words, in order to accept the door handle explanation, you need to ignore every one of these extremely improbable things. If it were someone on a website suggesting it, rather than The Metropolitan Police, you all know what they would be called and what they would be assumed to be wearing on their heads, don't you?
Secondly, they were fine for hours afterwards, so much so that they were able to drive to town, feed ducks, go for a meal, and then have a drink.
Thirdly, eye witness accounts of the couple on the bench suggest that they became seriously ill pretty much simultaneously. Certainly, there were no reports of one of the pair calling for help, or contacting the emergency services, which is what you would expect to have happened in the event of one becoming ill before the other.
Fourthly, during the duck feed, which took place just after the Skripals parked their car in Sainsbury's car park, and prior to their visit to Zizzis, Mr Skripal handed bread to some local boys, one of whom apparently ate a piece. I cannot think of a plausible explanation why this boy did not become ill if, as claimed, Mr Skripal's hands were contaminated at that time with a "military grade nerve agent".
Fifthly, either Mr Skripal or his daughter must have touched the parking machine at Sainsbury's car park, which was then touched by literally hundreds of people over the following days. Yet not one of these people were contaminated.
Sixthly, neither the door handle at Zizzis nor the door handle at The Mill were contaminated, despite the fact that either Mr Skripal or Yulia, or perhaps both, would have handled them when going into those venues.
Comment: A couple weeks ago, Slane asked the question: Where is Sergei Skripal? While he has seemingly recovered from the poisoning, he has been incommunicado ever since. We should really be asking another question in addition: Where is Nick Bailey? He too has seemingly disappeared. Why?