His grandfather, Auguste, broke high altitude records in the '30s by designing a balloon with a pressurized cockpit, and later became the inspiration for Professor Calculus in the Tintin comics.

WSJ: A Solar-Powered Plane Travels Light | WSJ. Magazine May 2013

They regularly drop in on Mr Gold, who quizzes them closely, his wild greying locks and well-stuffed shirt pocket giving him the air of a rumpled physics professor expounding an exotic retail calculus.

ECONOMIST: Face value