I dont know about Setanta but people tune in to watch them on SKY just look at the numbers on Royal's viewing figures thread. It always increased figures when the Klitschkos fight
In my experience, the general public are aware they exist but I don't think many would get their surname right and certainly wouldnt know one brother from the other. Ive spoken to countless people who have confused them with Valuev. Haye's done a lot of work promoting his fights on terrestrial TV in the UK (even been in an advert) and hasn't had to rely on the Klitschkos in the slightest. Widdow Maker is simply a clueless ****ing ****** who's man-love for the Klits causes him to blank out the facts when they don't suit him.
Naturally because there are two of them and they both hold versions of the Heavyweight title, then there is some confusion. I would hazard a guess that if you did a family fortunes of "Name a well known current or fromer British boxer ?" You would still get Frank Bruno, Chris Eubank, Henry Cooper, Amir Khan etc etc... Froch, Haye are not THAT well known outside of boxing circles. In the 80's and early 90's people who were on ITV were much more famous because they got hugh exposure. No one really cares about a PPV event with 70000 watching on TV and 30000 in the crowd. Some of the huge fights on ITV could get like 11 million viewers or more.
Even if they fought on setanta do you think the numbers accurately reflect how well they are known by the british public. Casual boxing fans are aware of them, casual sports fans have not. But Im sure by the end of the build up to this fight the klits will be very well known.
I guarantee that if Haye ends up fighting both Klits some of the casuals will be asking "why is he fighting that Klitschko again?" when he fights Vitali.