The snow currently falling across Europe is a timely reminder that butter was once a cold weather product. Before the days of universal refrigeration, it was harder to keep butter from going rancid or melting.

Not impossible, but a sufficient challenge to ensure it remained the prerogative of rich households. Where available, a buttery or a creamery were once built on the north side of a farmhouse, to avoid direct sunlight.

Larders, for the same reason, work best when sited on a north-facing wall. Marble shelves or slabs of slate ensured that food could be kept as cool as prevailing conditions allowed. A porous ceramic vessel filled with water will cool by evaporation and can keep butter fresher for longer.

But travelling with butter before the age of steam was generally avoided between about Easter and the onset of winter. It was just too hot for butter to survive the journey, with the exception of the canned clarified butter that was shipped to Brazil on vessels that returned laden with coffee.

Historically, Isigny sur Mer had the twin advantages of being able to send butter by ship and consolidate consignments from upstream producers on the river network that converged on the Vire estuary. Add to that the relative ease of navigating in wintry weather and it rapidly becomes clear why the ports of Paris, Rouen and Le Havre used to be such busy centres for the butter trade.