Electoral politics is a blood sport and some of the toughest fighters in the game are the campaign strategists who hone and sell their candidates' message.

Lynton Crosby is widely regarded as a master in the dark arts of political campaigning. He ran winning election campaigns in his native Australia for former prime minister John Howard. In the UK, he twice helped Boris Johnson win the London Mayor's office.

Opponents on the left have accused him of using grubby, divisive methods to further a conservative agenda. Is bare-knuckle politics good for democracy?

(Image: Lynton Crosby)