Two years ago it was the KK, then in January came the L.

But the female form is expanding at such a pace that even they are now not generous enough for our largest ladies.

An N cup size has been introduced - by no less than the Queen's underwear supplier.

It is not just that breasts are getting bigger though. It is the entire female body.

The increasing need for plus-size bras is due to the obesity epidemic, a report has found. The biggest bra does not come cheap. The 48N from Rigby and Peller, which supplies underwear to the Queen, costs £55.95 and is available in black or nude from the brand's seven high street stores. If even that fails to accommodate you, the company will tailor-make one.

Bravissimo launched the KK cup size two years ago. But with customers demanding even bigger sizes, the company launched the L cup in January. Rigby and Peller's N cup has swiftly followed.

One in five adults was classed as obese last year, and there has been a 2 per cent rise in obesity in women in just three years. A report by market researchers Mintel into trends in the UK lingerie market says this is to blame for growing cup sizes.

Analyst Tamara Sender said: 'As women in the UK are getting larger, with the average bra size having increased to a 34D, retailers are responding to growing demand for underwear in larger sizes.'

Obesity experts described the report's findings as 'worrying'.

Tam Fry, of the National Obesity Forum, said: 'Sizes are going up as always because people are eating the wrong food and not exercising enough. We are bombarded by advertisers and inundated with fast food joints.'

Women with large cup sizes are no longer restricted to matronly bras, the research found. Manufacturers have responded to demand for pretty, feminine lingerie.

Researchers also noticed an increase in demand for bra fittings, with one in five women measured for a bra last year. And larger bodies have boosted demand for body-moulding lingerie, with more than one in ten buying items such as control pants and corsets.