LONDON (Reuters Life!) - British women are happy nowadays to wear mini-skirts up until the age of 40, according to research by Debenhams department store.

Just 20 years ago, few women would dare to wear a mini-skirt after the age of 33, the store said.

"It shows that women now have an increasing confidence in their bodies and are happy to dress accordingly," it added in a statement.

"If this trend continues, there's no doubt that, within the next decade, women in their mid 40s and early 50s will rightly regard a mini-skirt as an essential part of their everyday wardrobe."

The figures emerged when the store examined the latest age profile of women buying short, 36-cm skirts over the past six months.

Their results show that it has jumped from an average age of 36-years-old at the start of millennium to 40 today.

Figures from 1980 showed that on average women stopped buying minis when they reached 33 years old -- a figure unchanged from the mid-1960s.

The store noted that experts believe that the popularity of intensive gym culture, providing women with well toned bodies for longer may be the reason.

The increasing number of British women living on their own may also be a factor.

The Debenhams' study showed that a modern woman's love affair with a mini-skirt begins at the age of 14 but that she doesn't buy her first one until the age of 16.

Instead, she flouts school rules by rolling up the waistband of the school uniform to give the impression of wearing a mini skirt.

Skirts get shorter between the ages of 16 and 19, reducing in size from 46 to 36 cm before reaching their shortest, a mere 32 cm, at the age of 23.

Skirt length increases slightly between the ages of 23 and 27, rising to 37 cm, possibly due to girls being in their first stable relationship, with no desire to attract attention, the store said.

However, it found short skirts suddenly zoom in popularity between the ages of 27 and 34, as those early relationships break down, and new relationships are formed.

The move into longer skirts begins irreversibly at 40 years old, when 46-cm skirts, still slightly above the knee are the norm.

From then on, skirt length increases dramatically, falling below the knee for the very first time since school days at the age of 42