In London, Raving with Raf Simons

LONDON — Later tonight, a party to celebrate a new Marc Jacobs flagship is set to close what some have started to call “Frieze Fashion Week,” a lineup of fashion events timed to coincide with the buzzy Frieze Art Fair. Everyone from Roksanda and Alexander McQueen to Celine and Off-White got in on the action. And let’s not forget Loewe, Byredo, Miu Miu, Moncler and Boss.

On Wednesday, art-loving designers Raf Simons and Jonathan…