It’s not been an easy sum­mer for fes­ti­vals, and each week brings fur­ther can­cel­la­tions. The good news is that a sur­feit of one-day music events is hap­pen­ing in Lon­don’s var­i­ous green spaces. Most fes­ti­vals have reached their final tick­et release, so if you’ve got your eye on some­thing, best snap those tick­ets up with­out fur­ther ado.…