The gorgeous great hall of the Queen’s House reverberated with the mellow, if unusual, tones of a double bass and harp duo working their way through a programme that included works by some of music’s greatest geniuses – Bach, Mozart, Schubert and Puccini among them. And I can say without fear of contradiction that bassist Valentina Ciardelli and harpist Anna Quiroga showed consummate skill as they interpreted the masterworks in this free Trinity Laban recital. But what turned a terrific performance into something magical was the inclusion of two pieces by the late great rock guitarist Frank Zappa. The duo, who call themselves The Girls In The Magnesium Dress – the title of a Zappa song – broke up an otherwise classical playlist with a storming version of the Californian’s 1969 composition Peaches En Regalia and ended with a stupendous cover, complete with chanting, of Cletus Awreetus-Awrightus from his 1972 album The Grand Wazoo. I’m old enough to have seen Zappa perform both tracks live and I’m convinced he’d have loved Valentina and Anna’s wild and wonderful renditions. I know I did.