It was pretty obvious, though, that that was what the question for the category of TV entrepreneurs would be and so easy to avoid if you don't watch the show. Clearly, as they got answers worth only 1 point and 2 points, the finalists did know the series.
With its repeat screening, Dragon's Den can attract up to 5m viewers, so I can see it being any more obscure than international flags, not when you're looking for the least obvious answers, whatever the question might be.