This is my take fwiw...

Elements of the intelligence community in Great Britain perpetrated this fake attack on the Skripals, perhaps with their cooperation, to either gin up support for the Tory government which is failing miserably in the Brexit negotiations...or to topple it as seems likely now that the truth about the poisoning case is starting to leak out.

Meanwhile, Tony Blair and his competent new "centrist" party are waiting patiently to take the stage...