As you would know the term Fourth Estate refers to the press, both in its explicit capacity of advocacy and in its implicit ability to frame political issues. The term goes back at least to Thomas Carlyle in the first half of the 19th century.
Novelist Jeffrey Archer in his work The Fourth Estate made this observation: "In May 1789, Louis XVI summoned to Versailles a full meeting of the 'Estate General'. The First Estate consisted of three hundred nobles. The Second Estate, three hundred clergy. The Third Estate, six hundred commoners. Some years later, after the French Revolution, Edmund Burke, looking up at the Press Gallery of the House of Commons, said, 'Yonder sits the Fourth Estate, and they are more important than them all.'" How true.
On this theme, add typewriters, guitar, bass and drums and you have Darwin's 4thEstate which provides a very interesting twist.