Performed amid a night garden of white helium balloons that float over a bare stage, Cie Nuua's Lento was one of the laureates of the 2012-13 edition of CircusNext and sets itself somewhere at the crossroads of juggling, puppetry and magie nouvelle. The company, who come from Finland, appear at the City of London Festival's Bowler Hat tent as part of a surprisingly lively programme of circus performances.