Ninety people were needed to lift it. That single fact — the sheer human labour required merely to move the Bayeux Tapestry from its display case last September — says more about the audacity of what France is now attempting than any ministerial press release could. Sometime in July, the 70-metre embroidered chronicle of the Norman Conquest, which has survived nearly a millennium of wars, revolutions and damp Norman air, will be loaded onto a lorry and driven 560 kilometres to London, where it will be displayed at the British Museum for nine months: only the third time in its long life that it has left the city of Bayeux at all. The engineering devised for the journey is, in its own quiet way, as ingenious as the tapestry itself.

The linen cloth will rest on a folding stand that concertinas into a compact form, which is then sealed inside an aluminium inner crate designed to regulate both temperature and humidity with precision. That crate is in turn held within an outer cage by twelve metal springs, positioned above and below, whose purpose is to intercept the vertical jolts of the road and redirect them as gentle horizontal rocking. "The idea is that the vertical shocks which will occur are transformed into horizontal shocks, causing the inner crate to rock to and fro like a baby in a cradle," said Cecilia Gauvin, an expert in art conservation — a description that is both scientifically exact and somehow tender. Two full rehearsals, conducted in February and April using facsimile copies travelling the same route beneath the Channel Tunnel, demonstrated that the system absorbs 96% of road vibration, reducing the tapestry's exposure to roughly the same level of disturbance it already experiences from the footsteps of museum visitors in Bayeux.

Kerstin Kracht, a vibration-reduction specialist on the team, noted that English roads showed measurably more potholes than French ones — an observation that provoked no diplomatic incident, but did require careful recalibration.