Deltic, it has been said on the news that the Green Godesses will not be responding to automatic alarms, so it appears as though the AFS will be on their in the terminal.
With regards to the two runway situation, I asked a similar question to a high-level security employee at STN a year or so ago with regards to a scenario where the AFS were attending a call on the outskirts of the airfield, he advised me that as long as the AFS were on the airport then operations can continue.
As I said he was security not AFS, so perhaps someone else can confirm that for me.