Behind the Mask, Another Mask: Gillian Wearing and Claude Cahun, National Portrait Gallery

'Under this mask, another mask. I will never finish removing all these faces.' So said Claude Cahun, the French Surrealist artist and photographer, who slipped from one gender to another long before Simone de Beauvoir or Judith Butler put pens to paper, or David Bowie got his mother in a whirl. Her identity was a performance, a series of masks. 'Masculine? Feminine? It depends on the situation.'

The work of this extraordinary artist is the subject of a new National Portrait Gallery exhibition, Behind the Mask, Another Mask. Cahun's work is presented alongside that of conceptual YBA photographer and Turner Prize-winner, Gillian Wearing; both explore the tangled landscapes of identity.

Born Lucy Schwob into a well-known Jewish intellectual family in Nantes, western France, Cahun changed her name – 'neuter is the only gender that always suits me', she explained – and began dressing androgynously. Along with her lover, artist Suzanne Malherbe, Cahun became closely associated with the Surrealists, painting her shaven head pink and gold and swanning around Parisian cafés. Man Ray adored her. André Breton called her 'one of the most curious spirits of our time'.

Together with Marlherbe, who had changed her own name to Marcel Moore, Cahun made photographs in which she dressed in androgynous disguise. In her most famous image, Self Portrait, we see her dressed as a strongman with kiss-curls, dumb-bells, black lipstick and lovehearts on her cheeks and thighs. Her leotard, complete with nipples and lips, reads: “I AM IN TRAINING DON’T KISS ME”. She dresses to transgress; this image is made to confound.

In 1937 the couple moved from Paris to the island of Jersey, which three years later was occupied by German troops. Cahun and Moore risked death by handing out resistance pamphlets, and they were eventually arrested. They were imprisoned, under sentence of death. With the liberation of the island in 1945, they were set free – only to find that their home had been ransacked and much of their work destroyed.

In other photographs on show at the NPG, a middle-aged Cahun clutches Nazi insignia between her teeth, on the day she was released from prison. Latterly, we see her bald, painted, a dandy, an aviator, a doll, a gentleman. There is no end to her performance.

These minute black and white photographs are placed alongside large-scale work by Gillian Wearing, who also photographs herself in various guises – including as Cahun. 'We were born in different times, we have different concerns, and we come from different backgrounds. She didn’t know me, yet I know her,' Wearing says.