Something is cooking...

[BIAD]

 
...Mr. G. says, Don't be in a Hurry and Don't Be Stupid, Plan ahead and Know Your Targets Body Movements
and pick a Crowded or Congested place, to make your exit from the victim, that makes it harder to remember
what you looked like or what you were wearing.

So in theory, the Skripals may have been infected in the restaurant, the public house before the meal
or anywhere on the walkway known as 'The Maltings'! Even the park where they sat.

Thanks.