Out to play: the best things to do around the UK this week

From open-air theatre in Liverpool to art in Edinburgh and live music at Knebworth – yes, really! – here’s our pick of attractions and events
Last week’s selection – many still going on

Two new exhibitions are launching for the reopening of City Art Centre on 12 September. Looking beyond the art deco and jazz of the era, Bright Shadows: Scottish Art in the 1920s aims to contrast artworks that deal with the losses of the first world war with pieces looking towards what was a new age of possibility. And City Art Centre at 40 includes highlights from the city’s collection, from 17th-century portraiture to contemporary abstract works. Mimi’s Bakehouse cafe on the ground floor has also reopened, serving brunch and pastries.
• Entrance to exhibitions free with allocated time slots booked in advance, edinburghmuseums.org.uk