Black squirrels and that missing gene

A ‘scurry’ of American grey squirrels was presented to the bride on the occasion of her marriage at Castleforbes, County Longford, in 1910. The descendents of these aliens are thriving now east of the Shannon. The species had been introduced to Britain 40 years earlier; having these exotic creatures on your country estate soon became a fashion statement.

A black squirrel was seen in Woburn, Bedfordshire, in 1912. Three decades later, the dark variety had become relatively common in three midland shires. There are now thought to be about 25,000 black ones nationwide, outnumbering greys by three-to-one in some areas.