"Our governance structure is in danger of falling short of modern standards of best practice," he said.
"As the country's national sport, we ought to be leading the way. There is a wind of change blowing through global sporting governance and we need to ensure we do not get left behind."
William, who has backed outgoing FA Chairman Greg Dyke's efforts to reform the FA Council, urged the assembled guests, many of whom are board members, to play a more proactive role in ushering in changes at the governing body.
"I know the organisation is currently reviewing this issue and there is an opportunity to seize the initiative by the way in which we reform ourselves," he said.
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"This is an emotive issue, and it is one that you all have a stake in deciding."
William, whose favourite Premier League club Aston Villa appear destined for relegation this season, is hoping that leaders Leicester City find a happy ending to their fairytale season by winning the title.
"I'm dying for Leicester to win (the league). It will be good for the game," he said.
Leicester currently lead the division by seven points ahead of Tottenham Hotspur and will lift the title if they win four of their remaining six games.
(Reporting by Simon Jennings in Bengaluru; Editing by John O'Brien)
