An entire era is named for her and symbolizes uptight attitudes about sensuality.

But it turns out Queen Victoria may have had a behind-closed-doors side never seen by the 19th Century public. Imperious, unapproachable, often speaking in an aloof plural first person — as in, “We are not amused” — she gave her name to the Victorian Age, during which pregnant women went into seclusion, piano legs wore trousers and doctors did not examine female patients, instead used dolls on which women demurely pointed to the area of their symptoms.

However, Her Majesty posed for a racy portrait that Windsor Castle has kept behind closed doors for more than a century.

The never-before-unveiled Queen Victoria (Painting courtesy Buckingham Palace)

The portrait was painted in 1843 by Franz Xaver Winterhalter, commissioned by Victoria and given to Prince Albert, her beloved

husband. Under British custom, when a female is the head of state, she bears the title “queen,” but her husband is only a duke — and bears the title of “prince.”

Six year into her reign, the 24-year-old Victoria commissioned the painting, which she gave to her husband as a surprise birthday present.

“It was Albert’s favorite portrait of her,” says Desmond Shawe-Taylor, official Surveyor of the Queen’s Pictures.

Albert thought it was so daring that he kept it in a private room at Windsor Castle and did not let anyone else view it.

“It was clearly intended as a loving expression,” said Shawe-Taylor, “and reads as if it is extremely intimate and alluring – that secret ‘for your eyes only’ effect.”

Even after Victoria’s death, the painting considered to be too overtly sexual to be shown to the public. Its existence was not revealed until 1977, more than 130 years after it was painted.

BBC is unveiling the intimate portrait as part of a 2012 series highlighting the royal family’s collection of artworks. Also revealed is a book written by King Henry VIII in defense of the Catholic church. It was written before his famous rift with the Vatican — which resulted in the founding of the Church of England after the Pope refused annul for Henry’s marriage.

Timed to coincide with the Queen’s Diamond Jubilee, the eight-part series features 50 of the most fascinating objects among the million or more items collected by Britain’s kings and queens over hundreds of years.

Also featured will be a photograph from Queen Victoria’s family album, taken when she attended the wedding of her grandson, the Grand Duke of Hesse, to Victoria Melita of Saxe-Coburg and Gotha.

Victoria sits in the center of the picture, taken in Coburg, Germany, in 1894.

To her right is her grandson, Germany’s Kaiser Wilhelm II, who would lead his country to war against Britain in World War I. Immediately behind him is Czar Nicholas II of Russia, who was assassinated with his wife and children in 1918 during the Russian Revolution.