The organisation, he wrote, lacked transparency and was led by a clique that had barely changed in a decade.

Three years later, the 36-year-old Iraq and Afghanistan veteran, military scholar and son-in-law of Malcolm and Lucy Turnbull faces the daunting task of navigating the very labyrinth and untangling the complex hierarchies he once complained about after the league's grass roots elected him their new state president.

Vowing to clean up the organisation after months of revelations about alleged financial improprieties including credit card fraud, Brown swept aside the rusted-on leadership of Vietnam veteran John Haines, who had sat on the council for 21 years and faced stern criticism from many quarters including the NSW government for not moving more decisively to tackle the financial scandal.

Already a regular media commentator on military and foreign affairs issues as research director at the US Studies Centre at the University of NSW, Brown will become the face of the league as it is subjected to a Royal Commission-style probe over the financial scandals.

He will have to juggle several priorities amid high expectations. As well as reforming an organisation long driven by personalities and tradition, Brown wants the RSL to bring some scientific rigour to veterans policy which he says was shaped by the Vietnam era and may need reform.

"We need smart people who can look at those questions and if there is a case to government for change, take that up to the government, both federal and state."

There will be considerable enthusiasm within a new, younger council for the league to be more vocal advocates. Mick Bainbridge, a former commando who has done four tours of Afghanistan and one of East Timor and has become the NSW league's youngest ever councillor at age 32, said a large part of the job will be "making sure that no rights of veterans are eroded as they have been for the last 10 or 15 years and holding all levels of government accountable for that".

Brown also wants to end the image of the RSL as an old boys club, attracting more younger veterans of the post-East Timor period and more women.

But he also stresses that sorting out the financial allegations will dominate much of the new council's first year. It will be a "stabilisation phase".

"Based on the very limited briefings I've had so far, the governance situation as it existed in the past seven years is worse than I thought," he said.

That's not to mention juggling his own priorities. Brown has a full-time job involving significant travel and two young children with wife Daisy Turnbull Brown, who tweeted after his election win: "Huge congrats @captainbrown, you got some work ahead of you."

There is widespread speculation, including within the RSL, that Brown will eventually make a tilt at politics himself.

Inevitably there are murmurings that this is a stepping stone, though it can't be disputed that Brown has a lengthy track record in pushing for a paradigm shift in veterans affairs that better recognises the needs of younger veterans. His has been one of the most prominent voices arguing that our obsession with Anzac mythology is coming at the cost of a new generation of war returnees who are facing problems with post-traumatic stress disorder and elevated suicide rates.

Brown will step down as president of the Liberal Party's Paddington branch. But he will remain a party member, saying that RSL members belong to political parties, churches and unions though the organisation is non-partisan and non-sectarian.

He said he was "confident about being able to advocate for the best interests of veterans irrespective of which party is in government".