From Griffin's point of view, there were many upsides and very few downsides. It was essentially an hour-long interview, where he managed to make himself look less odious than he really is.
As has already been pointed out, he was able to almost assume underdog status. And by zeroing in purely on immigration, something that does evoke impassioned viewpoints, the panel didn't really catch him out. Just one example: he got away with airing his views on the NHS, which survives thanks to a lot of non-UK staff. Does he think they should all be packed off? Neither the panel nor the BBC bothered to find out.
Dirk Singer, co-founder, Cow PR.