Secret postcard art designs displayed at Royal College of Arts Students help to display some of the postcards from the 2700 that are to be included in the RCA Secret Postcard sale at the Royal College of Art in south London on March 13, 2013. Now in it's 20th year, the sale sees work from students and guest contributors provide anonymous work that sells for £45 each. The buyer only gets to learn the identity of the artist after making the purchase. Images