The postcard above was published by Statics London and is titled "Tears of a Clown." The postcard does not identify the clown or poster. I learned from other sources that the clown on the poster is Lou Jacobs, and the poster is of 1940s vintage.
The clown face of Lou Jacobs (1903-1992) was used on the first circus stamp issued by the United States, the 5-cent American Circus stamp of 1966. That stamp was issued to honor the American Circus on the centenary of the birth of John Ringling. Ringling and his four brothers founded the Ringling Brothers Circus and later acquired the Barnum and Bailey Circus in London. The postcard below shows the Ringling Brothers, Barnum, and Bailey.
The United States Postal Service recently issued a sheet of Vintage Circus Posters Stamps featuring reproductions of eight vintage circus posters on May 5, 2014. The back of the sheet has a brief discussion of the history and purpose of circus posters.
This is a post for Sunday Stamps at Viridian's Postcard Blog