how does J.B. Priestley convey his political views through Eric Birling, in An Inspector Calls?

Eric Birling is used by Priestley to symbolize a more hopeful future for post-war Britain. At the time when J.B. Priestley wrote An Inspector Calls, Britain had emerged from World War II on the brink of bankruptcy. There was a widespread consensus in the country for major political and economic change to help meet the monumental challenges that Britain faced. The British people shocked the world by rejecting Churchill and electing a Labour government committed to a radical program of socialism, a political philosophy endorsed by Priestley.
Eric is different to his father, an unfeeling capitalist obsessed with making money and social status. Unlike Mr. Burling, Eric has a social conscience, recognizing that the family's treatment of Eva Smith was morally indefensible. Though initially lacking in confidence and dominated by his overbearing father, Eric becomes more assertive as the play progresses. He openly challenges his father's economic philosophy, loudly proclaiming that Eva was entitled to push for higher wages and shouldn't have been fired.
Eric, like J.B. Priestley, has an understanding of the exploitative side of capitalism and the damaging effect it often has on people. Most importantly of all, he comes to recognize the way in which the unfettered capitalism of his father preaches restraint and personal responsibility to those at the bottom while allowing those at the top to get away—sometimes literally—with murder. It is this heartless system that Eric rejects, just as J.B. Priestley and a large section of the British population did in 1945.