At the Holland Festival, Mackenzie is opening the doors to a new avant-garde among the audience.

The neat couple next to me, in the front row at the Holland Festival press conference, hadn't counted on it for a moment. Four members of the Netherlands Chamber Choir starting to undress one by one down to their pecker-sized nakedness. A giggle, a little cough, but hey, this is the Holland Festival, they told each other. So also not too surprised when three of the singers drape themselves naked on top of each other, after which the fourth starts slapping and kicking them, and so on, thanks to...