A rare chance to see Derek Bailey and Jeremy Marre's landmark series about improvisation and invention in music – screening in full, in stereo and across a single afternoon.

So Watt is an annual event within the London Jazz Festival which unearths rarities from the television archives. This year's event is specially extended to mark the twentieth anniversary of Derek Bailey's death.

In 1989, Channel 4 invited guitarist Derek Bailey to explore improvisation across the music spectrum, throughout the world, and down the ages. According to the original pitch, On the Edge is a series about 'the all-pervasive presence and significance of improvisation in music.'

Travelling the globe, Bailey meets John Zorn, Eugene Chadbourne, Jerry Garcia, Max Roach, George Lewis, flamenco dancers, slide guitarists in Tennessee, 'classical' Indian musicians, salsa bands, and blues legend Buddy Guy. The documentarian Jeremy Marre selects stunning locations for this feast for the eyes and ears.