Interesting that you were called upon to actually "gas" people Danny. When you call them "guinea pigs", were they volunteers do you know? I seem to recall that Porton Down itself were supplied with volunteers in the 60's, though the volunteering bit was supposedly for research into the common cold! As you say, the effects could be quite devastating (the whole point of the exercise of course), even more so with some of Porton's more exotic cocktails.
As for yourselves, the previously described procedure of aiming out to sea and abandoning the aircraft would seem to have been the best emergency option, if available. The thought of trying to extricate yourselves from a wrecked machine swamped in Mustard Gas is pretty grim.
I've just read your Peoples War link Danny. Very descriptive indeed. You would appear to have a rival!