It’s bad enough for the embattled board of AGL Energy that Australia’s three big proxy firms have handed Mike Cannon-Brookes an important victory in the billionaire’s battle to install four new directors at the company.

What’s worse is that the proxy advisers’ reports could allow Cannon-Brookes to keep chipping away at the credibility of chairman Patricia McKenzie, potentially opening up the opportunity for Cannon-Brookes to shape the selection of AGL’s next chief executive and chairman in a way an 11.3 per cent shareholder usually couldn’t.