Tess Daly and Claudia Winkleman host the launch of the 20th series, joined by judges Shirley Ballas, Anton Du Beke, Craig Revel Horwood and Motsi Mabuse as they welcome 15 new celebrities to the Strictly ballroom. Featuring a guest appearance by John Legend, and last year's champions Rose Ayling-Ellis and Giovanni Pernice reprising their winning routine