A seemingly endless tapestry of postcards greets visitors to the latest Gilbert & George exhibition at White Cube. The aesthetic quality of the show is tangible from the start, even when one is not quite sure of the content of the pictures. The overall effect is that of giant, multicoloured quilts that cover the walls of two rooms. And then you get closer to the pictures; and each one is a surprise.

Each picture is comprised of thirteen identical postcards arranged in the shape of a square urethra. The creation of the ‘Urethra Postcard Pictures’ was an automated process. Once thirteen identical flyers or postcards had been collected, they were simply arranged and the title was taken from something within the postcard to describe the picture. The titles of the pictures are works of art on their own and sound like poetry. Their beauty lies in their simplicity and their usefulness in describing each work as fully as possible.

The urethra symbol was not randomly chosen as a scandalous geometric arrangement for postcards. It is a sexual symbol and a representation of libertarianism – very simply put, the freedom of expression, ideas and actions. The urethra appears to free the meanings held within the ordinary postcard.

Some of the postcards are taken from flyers found mainly in London telephone boxes. The flyers advertise sexual services from rent-boys, prostitutes and ‘masseurs’ as well as performance enhancing drugs and sexual education. You would probably not blink twice at them in a normal situation. Arranged in the urethra symbol, the postcards are freed from the constraints of seediness and the mundane. The flyers become something – shocking, sad, wistful, sometimes funny – whatever you imagine really; but a distinct connection to the reality of the London underworld.

The ‘Union Flag Picture Postcard Pictures’ are produced using tourist postcards of quintessentially British and eternally recognisable subjects. The buildings and symbols of London are thrust out of the pictures and almost literally into our faces. The commonplace postcard turns into a representation of London from the outside. There is none of the grime of the ‘Flyer Pictures’ and the ‘London Telephone Box Card Pictures’ in these, but perhaps more of what is artificial and yet on display for everyone to see.

Cindy Sherman’s current photo installation at the Sprüth Magers gallery is an excellent and thought provoking companion to the Gilbert & George show. Sherman gives us larger than life photographs of herself in fairytale costumes against the slightly macabre backdrop of a 19th Century Central Park. As much as the ‘Urethra Postcard Pictures’ regurgitate London’s hidden identities, Sherman’s work is equally about American identity and some of its apparently sinister sexual undercurrents. The artwork itself, without going into any deep or convoluted meaning, is very weird, wonderful and definitely something to see in itself.

White Cube gallery until 19th Feb