How do they get these figures? If it's based on how many sets were tuned in, (though don't know how they can monitor this), then the figure is an approximation as some people may have just had it on for company, (e.g. old people, shop sets left on etc). Those that were genuinely watching may have comprised more than one person, (there were 3 of us last night).
Just curious as to how they seem to know how many watched an event.