Super-size uniforms on offer in high street

An online trial of Marks & Spencer's new Plus schoolwear range caters for four-year-olds with waistlines of up to 23ins – a size usually worn by eight-year-olds, according to the retailer's own guide.

Campaigners said the move by M&S was simply commercial recognition of what they had known for some time – that obesity is a growing problem among pre-schoolers and younger pupils.

The Plus range has been introduced as part of a trial prompted by demand from parents, M&S said. It caters for ages three to 16. Trouser and skirt sizes go up to a 41-inch waist.

But it is the large sizes for primary school entrants that will cause most concern, amid fears Britain could be facing a growing obesity problem.

Tam Fry, of the National Obesity Forum, said: "This is the actual commercial recognition of what we have known for some time – that obesity in pre-schoolers is building up.

"Now 27 per cent of entrants to primary schools are overweight or obese."

Mr Fry said he had no issue with M&S offering the range, adding that the firm had been among the better retailers when it comes to giving clear information on their food range.

But he called for a collective effort to curb obesity.

Mr Fry said: "Parents should not fail in their responsibility – it is they that put food in their children's mouths, send their children out to play.

M&S introduced the Plus range earlier this month with little fanfare.

A spokesman for the retailer said: "It is a small online trial running in response to customer demand."