Circus Post is a series of short films made by Crying Out Loud and film-maker Deborah May contextualising the development of contemporary circus over the past 40 years.

Photographer Bertil Nilsson talks about his book  Undisclosed, a collection of black and white stills of circus artists pictured naked as they work on their skills.

Nilsson spent five years travelling Europe and North America to photograph his subjects in their natural element, capturing them at work in training spaces and studios and affording us a glimpse of the sheer physicality that lies behind each circus performance.

Yet while much is revealed, more is hidden: for all that they lay the circus artist bare, Nilsson’s photographs retain an enigmatic energy, the compositions expressive and empty, the actions of each subject frozen within a flowing silence