Thanks for the responses. If I remember correctly 27R was still the main landing runway on Friday evening promulgated by the ATIS as we'd both expressed surprise at the decision, nor did we get the late change of runway instructions you normally get from Director. Neither I nor the Skipper were particularly happy with the decision but we both know there's normally no chance of the other runway without declaring an emergency, which is a rather extreme course of action. The dealternation occurred as we were on final approach with two of the previous four aircraft going around due to windshear and another reporting severe turbulence. We did actually ask for a visual switch at about 6d but were told it was unavailable as we were 3 miles behind a heavy for 27L. Just seemed a peculiar chain of events on the day.