It appears to be partly who's popular with the public and their 'followers' and partly true dance ability.
Although I haven't remarked on Greg Wise so far I must admit I find him a bit annoying and a bit of a 'luvvie'. He's also not a great dancer. As far as dancing ability goes IMO I think Judy Greg and Dan(who's a lovely man so hope it's not him who goes tonight) are the weakest.
In the final I like the best dancer to win. Last year it wasn't, but fair enough Bill did amazing from having no previous dancing experience.
What was the name of the corner shop you went to as a child?
How will the VAT cut be funded?

