Baroness Hayman of Ullock, the parliamentary under-secretary of state for biosecurity, borders and animals, has been widely derided over the blue Dolce & Gabbana dress, which retailed for £955 (around €1,100).

Grey squirrels — an invasive American import — have been blamed for a sharp decline in the red squirrel population in Britain and Ireland, as they out-compete them for food while spreading deadly pathogens.

In a Facebook comment under photos of the conference, Ian Glendinning, chair of the Upper Coquetdale Red Squirrel Group, said the baroness’s choice of clothing was “completely bizarre”.

He said: “The event was a conference about red squirrel conservation and she turned up wearing a lovely dress decorated with grey squirrels. Incredible.

“You have to admit, it’s a rather amusing faux pas, a definite fashion malfunction.”

The conference was organised by the UK Squirrel Accord to mark its 10th anniversary, and was sponsored by the Red Squirrel Survival Trust and the University of Greenwich.