The NPG's new exhibition, First Actresses: Nell Gwyn to Sarah Siddons, groups together portraits of many famous ladies from the 17th and 18th Centuries. The star attraction is sure to be this memorable piece in which king's mistress and noted minx Nell Gwyn bares all in a saucy sitting for Simon Verelst in 1680.
The portrait has been in private hands since the 1940s, and was only recently identified as Nell Gwyn. Some prudish Victorian had painted over her more striking features, now newly revealed by the gallery's conservationists.
You can see the portrait alongside actresses of more modest couture at the gallery from 20 October to 8 January. Entrance is £11.
Fans of arty smut might enjoy our scientific analysis of all the breasts and genitals in the National Gallery.