Taken from Strictly site
"The Strictly Come Dancing semi-final will feature the show's first ever swing-a-thon.

This year's semi-final will be split over three shows with the first airing on Friday, December 10 at 9pm. After performing one regular dance on the Friday show, all the couples will compete in the swing-a-thon.

During the competitive dance, head judge Len Goodman will eliminate pairings one at a time, depending on who the panel believe is performing the best. The couples must keep on dancing until they are voted out of the contest.

The first couple kicked off will pick up one point, the second couple two, the third couple three and so on. Those scores will be added to the total marks they picked up for their first dance.

The BBC production team have described the swing-a-thon as "the ultimate test of style and stamina". It has previously been used on the US version of the ballroom show, Dancing With The Stars.

All the Friday night scores will be combined with the marks from the Saturday show, before phonelines are opened for the public to vote for their favourite couple.

This year's final will feature three celebrities, so there will be a double elimination on the Sunday show, unless a contestant is forced to pull out with an injury."

I thought Ann had actually tried to do a proper dance. I do admire her but she should have gone weeks ago.

I missed last night, I was so tired I fell asleep!

Did anyone watch the Final? I was routing for Kara, but had a feeling she wouldn't win

Matt surprised me, I didn't think he(they) was very good on the night but I think it was down to Aliona?

Also shocked when Pamela & James were eliminated

Although Kara wasn't perfect & injured I am glad she won

Brucie was a tad jaded bless him

Loved it. Excellent result. I thought Matt was very good but his partner`s choreography was too experimental for a compo like this.

I agree re Aliona'a choeography.

Artem was so emotional all the way through wasn't he......

Surprised at no one special singing - Paloma Faith!!!!

Loved it but would have loved to see Pamela in the final against Kara. Was fab though!