Bercow was a Conservative member of Parliament for 12 years until being elected in 2009 to the neutral role of Speaker, responsible for running House of Commons business and interpreting its rules of procedure.

He enraged the Conservative governments of prime minister Theresa May and her successor, Boris Johnson, by giving backbench legislators chances to stymie proposed legislation about the UK's exit from the European Union.

He became a hero to opponents of Brexit and a villain to its supporters, and was recognised around the world for his loud ties and even louder calls of "Order!" in the raucous lower house. He stepped down in 2019.

He insisted he was neutral in his handling of Brexit debates, though after leaving office he called the UK's 2016 vote to quit the EU a historic mistake.

Bercow began his political career in the 1980s as a right-wing acolyte of then-prime minister Margaret Thatcher, but has moved to the left over the years.

He angered some on the political right by saying in 2017 that then-president Donald Trump should not be allowed to address parliament.

Bercow is a strong critic of Johnson, a champion of Brexit. He told The Observer newspaper that the Conservatives under Johnson had become "reactionary, populist, nationalistic and sometimes even xenophobic".

Justice Secretary Robert Buckland rejected the characterisation of the party as xenophobic, and said Bercow's decision to forgo political neutrality "actually has the effect of diminishing the force of his voice in politics".

Australian Associated Press