Alan,
ISTARS - Intelligence, Surveillance, Target Acquisition and the Reconnaissance.
There are only two R1s in existence XV249 and XW664, not XW665 as I said above, it having been retired some months ago. Rare to see them in this country as they are usually deployed to Aghanistan. However, recent heightening of the terrorist threat here is keeping one busy in our skies along with some other newer types which should be out in Afghanistan helping our troops.
Tom