The last time I entered the UK, via Birmingham Airport, they had all non-EU citizens stand at a particular point once they got to the front of the line at immigration, prior to approaching one of the immigration officers. I realized afterwards that they had one of those backscatter "nude-o-scopes" that was pointed at that point.
What ticked me off, though, is that the viewing monitor is in full view of anyone walking by, on the way out to baggage claim (with a few immigration offiers huddled around it) -- I took a glance and could see the figure of the man at the front of the line at that point. grrrr!!!