The couple received a standing ovation after hosts Bruce Forsyth and Tess Daly revealed the result, which came after the couple performed the American Smooth to Robbie Williams' "Do Nothing Till You Hear From Me" for the second time.
Joining Louisa and Vincent in the bottom two were Emma Bunton and Darren Bennett, who were clearly surprised to have made it through to the semi-final after appearing in the bottom two in previous weeks.
For more on tonight's Strictly, see the running order, the judges' comments and scores, dance-by-dance, and details on the bottom two dance-off.
