The Harding and Roth argument in the Guardian article shared by Mistigri is half baked and full of holes.
The election result in Russia is a foregone conclusion. Putin doesn't need an attack on a former spy to win. Putin doesn't need any more decoration to the scenario of everyone ganging up on Russia. He is not desperately clinging to power.
Former senior Foreign Office adviser...'“Moscow’s goal is to demonstrate the UK’s weakness and isolation and to drive a wedge between us and other countries."' - exactly how does this achieve that end? Even Trump has made some noises to the effect that this was not a good thing. If Moscow is all in favour of Brexit how does the solidarity of Guy Verhofstadt over the assassination attempt fit in with this theory too? An incident of this sort is almost guaranteed to raise the hackles of Europe.
"If May fails to react adequately, she would appear weak. If she tries to fight back against Russia, she would discover the limits of collective solidarity," the adviser suggested.'
Sorry again, but Guy Verhofstadt has scuppered that argument, unless the adviser feels the EU doesn't count.
Why is the presence of Russian emigres in London a sore point for Russia? Why would forcing them out be 'useful and beneficial to Putin'? Many of them are prominent Putin supporters. A detective novelist and Kabuki theatre expert is the author of this theory - maybe Harding and Roth should take up crime fiction too?
Just musing here, but:
Is it possible that Skripal was chosen because his residence close to Porton Down made it handier for British operatives to bump him off? He was an isolated and vulnerable figure - a foreigner and former spy - and demonstrably not given any sort of protection by the Home Office or any security arm. Was TM trying to generate some international outrage on Britain's behalf? Some expression of solidarity and friendliness on the part of the EU? Those results have happened. Was May's government hoping to elicit some shot to the foot response by Corbyn? That has possibly happened too - history will tell - but maybe TM went too far and tried to make sure her mark would behave as hoped by not briefing him. The only real worry that the Tories have is Labour. Hence the incredibly misguided (in hindsight) general election instead of planning for Brexit, after all. Hence all the dog whistling (Corbyn's hat, and all the rest of the attempts to associate him with unsavoury elements - the IRA, the Communists).
Alternatively, was Skripal a double-double agent, somehow turned back to Russian allegiance while in prison there for spying for Britain, and sent to live close to not one but two incredibly sensitive military-scientific installations, Porton Down and Winterbourne Gunner (4 miles from Salisbury, the Defence CBRN Centre, providing training for chemical, biological, radiological and nuclear events)?
Porton Down shares its 7,000 acre site with private companies and research labs.
Who works in those places? Did Skripal have any contacts with people working on those sites? Coverage of the incident has mentioned the sleepy, quaint character of Salisbury, but there are two extremely sensitive sites within walking distance and presumably many employees of those sites live in the town.
Why did the Home Office let this former spy - and not just a spy but a double agent - settle so close to such sensitive installations?