A skinny-dipper.

 

"The climax is when I find a colossal chasm in the rocks - miles away from civilisation - climb an enormous distance down to rocky shore & undress & bathe stark naked. The sheer sensual exstasy [sic] of it! ... Utter bliss!"

 

Britten's Children, John Bridcut, 2005

 

There is a photo of Britten naked posing beside a pool in a recent biography.

 

Benjamin Britten, A Life in the Twentieth Century, Paul Kildea, 2013. Plate 17.