Who What When Where How & Why, 25-year retrospective of the one-time YBA at the Newport Street Gallery, references more artists in its six galleries than you often find in a whole collection, from 20th century giants such as Andy Warhol, Robert Morris, Rene Magritte and Jackson Pollock to masters from the Greek classical age by way of the French Revolution as envisioned by Jacques-Louis David and Marie Tussaud. All these are striking – but not as striking as some of his more recent creations which involve taking an everyday found object such as a polystyrene cup, making a bronze model of it and then painting it to look like the used, discarded item that inspired it in the first place. Turk has done the same with old sleepingbags, plastic rubbish sacks, cardboard boxes and, astonishingly, apple cores and burnt matches. This triple-switch of junk masquerading as art masquerading as junk is a brilliant metaphor for today’s society in which even the coarsest materials and individuals can become transcendent. In this case, Turk is the alchemist who has discovered the secret of turning base metal into gold.