For Airbus, which makes the wings for all its passenger jets in Britain, that worst-case scenario would occur if Britain is no longer part of the EU aviation safety certification agency, EASA, which gives planes and parts approvals so that they can fly.

According to Airbus Chief Executive Tom Enders, certification for thousands of parts that are part of the supply chain, part of their aircraft, would fall apart, and that could be a very troubling situation for them and could eventually lead to a standstill of production. Guillaume Faury, boss of Airbus’s plane making unit, said planes could also be grounded.