The Morrison government's stunning backflip on mortgage broker pay was engineered by the prime minister's celebrity friend Mark Bouris, aided by his former flatmate, Assistant Treasurer Stuart Robert, and clinched via a textbook case of effective grassroots lobbying.

Just weeks after the government agreed to the banking royal commission's call to ban brokers' trailing commissions to protect consumers, an ashen-faced Treasurer Josh Frydenberg announced the backdown on Tuesday.