Katie Derham considers the world of early jazz dance with Strictly Come Dancing choreographer Ryan Francois, from its roots in the notorious world of black slavery, to Harlem in the 1920s, and beyond. A popular feature of BBC One's "Strictly Come Dancing" are the jazz routines - the Charleston and Jive, with their colour, excitement and joie de vivre. Katie Derham looks back on the journey that these dance styles undertook before arriving at their modern form and considers the stories, music and movement that shaped them. With Katie is one of Strictly's regular choreographers, Ryan Francois, a specialist in jazz dance, who helps to unpick the origins of one of dance's most vibrant forms.