But this all involves a powered sleigh. The reindeer themselves still need to be able to fly. This could be achieved by genetic engineering, altering the reindeer so their lungs are huge and filled with helium; they could even be born with wings and stabiliser fins. Or, as Professor Ian Stewart, Warwick University maths professor and occasional Telegraph contributor, points out: “Reindeer have a curious arrangement of gadgetry on top of their heads which we call antlers and naively assume exist for the males to do battle and to win females. This is absolute nonsense. The antlers are actually fractal vortex-shedding devices. We are talking not aerodynamics here, but antlaerodynamics.” At the speeds the reindeer have to travel to deliver gifts, their antler-tips would, apparently, create enough lift to allow them to fly.