In response to the ASA, the retailer said the 5’9″ model’s pose was chosen “specifically to display the leggings’ fit on both straight and bent legs”, and that the image, which was shot nearly two years ago, was created with a “strong sense of responsibility”.

A spokesperson added a Next stylist and product image manager met the model in person and “did not have any concerns about her health”.

In its ruling, the ASA acknowledged the model’s face “did not appear to be gaunt and her arms, while slim, did not display any protruding bones”.

But it said: “Because the pose, camera angle and styling in the ad investigated strongly emphasised the slimness of the model’s legs, we considered that the ad gave the impression that the model was unhealthily thin.”

Next said it had not used digital retouching to alter the model’s appearance but did digitally alter the appearance of the leggings by bringing them down further towards the model’s ankle on both legs.

This was not said to alter the model’s natural proportions.

The ASA told Next that its advert breached the code for social responsibility.

It said the ad must not appear again in its current form, and that Next should ensure the images in their ads were “prepared responsibly and did not portray models as being unhealthily thin.”

“You do wonder how it got through,” fashion journalist Victoria Moss told BBC Breakfast.

“Next are usually very commercial, their models are very ‘girl-next-door’. This model has ‘the look’ of a model,” she said, adding however that it was “important not to stigmatise either way”.