Petit Manuel looked at her with eyes like crushed flowers.

The performance began an hour later. The dark-rimmed clouds were lit by the sun setting behind the mesa, the air crossed by wraiths of cirrus like the gilded frames of the immense paintings to come. Van Eyck’s glider rose in a spiral towards the face of the first cloud, stalling and climbing again as the turbulent updraughts threw him across the air.

As the cheekbones began to appear, as smooth and lifeless as carved foam, applause rang out from the guests seated on the terrace. Five minutes later, when Van Eyck’s glider swooped down onto the lake, I could see that he had excelled himself. Lit by the searchlights, and with the overture to Tristan sounding from the loudspeaker on the slopes of the mesa, as if inflating this huge bauble, the portrait of Leonora moved overhead, a faint rain falling from it. By luck the cloud remained stable until it passed the shoreline, and then broke up in the evening air as if ripped from the sky by an irritated hand.

Petit Manuel began his ascent, sailing in on a dark-edged cloud like an urchin accosting a bad-tempered matron. He soared to and fro, as if unsure how to shape this unpredictable column of vapour, then began to carve it into the approximate contours of a woman’s head. He seemed more nervous than I had ever seen him. As he finished a second round of applause broke out, soon followed by laughter and ironic cheers.

The cloud, sculptured into a flattering likeness of Leonora, had begun to tilt, rotating in the disturbed air. The jaw lengthened, the glazed smile became that of an idiot. Within a minute the gigantic head of Leonora Chanel hung upside down above us.

Discreetly I ordered the searchlights switched off, and the audience’s attention turned to Nolan’s black-winged glider as it climbed towards the next cloud.