<<Errmmm you don't stop for thunderstorms at Heathrow?? Must be fairly wussy storms then...I didn't think you were allowed to fuel an aircraft on the ramp if there was lightning around? Ground stops occur here for that very reason...plus a lot of the airlines don't seem to want to fly through them.>>
I was a controller dealing with Heathrow traffic for 31 years and recall very few times times when landings or take-offs stopped for more than a few minutes when there was a storm overhead. When the storm is close by, aircraft fly round it or the departure route is varied. I don't know about the refuelling restrictions; they may well exist. If we shut major airfields over here every time there was a Cb around it would be more chaotic than when we have snow!!