Barbican, London; onlineThis year's festival opens with a formally rigorous work from the South African choreographer and a film premiere from Lea Anderson London's annual international Dance Umbrella festival is at once a venerable institution and a crucible for the new. Founded by Val Bourne in 1978 and nurtured by Betsy Gregory, this year's festival is dedicated to the memory of Emma Gladstone, who ran it with pio…
