Madame X (Madame Pierre Gautreau)

John Singer Sargent was an American artist, born in Florence, to American parents, and trained in Paris.

He became the leading portrait painter of his generation.

By the early 1880s, he was well-established in Paris, painting portraits for the wealthy elite.

Madame X was meant to be his masterpiece - a painting which would cement his place at the top of Parisian society.

However it went tragically wrong - and ended his career in France.

The subject is Virginie Amélie Avegno Gautreau, an American-born socialite, married to a wealthy banker and living in Paris - famous for her beauty and chalk-white complexion (said to be achieved by lavender powder and possibly arsenic).

She agreed to sit for Sargent hoping for a glamorous portrait - but got a scandal instead.

When Sargent exhibited the painting at the Paris Salon of 1884, the public was outraged - not by the low neckline or by her arrogant pose, but by a single strap which was represented slipping off her shoulder.

The reaction was so fierce (women apparently shouting 'quelle horreur' and Gautreau's family asking for the painting to be removed) that Sargent repainted the strap in its proper position - if you look closely you can still its former outline.

Sargent then left Paris for London, where he rebuilt his career and never really looked back.

He kept the painting in his studio and sold it to the Met 30 years later, the year before he died.

In doing so, he titled the painting Madame X - in order to protect what was left of Gautreau's reputation - however who she was was an open secret at the time.