Long a Labor Party right-wing chieftain in Victoria, he piled up favours among allies whose entry into Parliament he helped engineer – including the current leader, Bill Shorten – and loathing among those, like Simon Crean, whose careers he tried to end.

One-time leader Mark Latham named Conroy as one of the "three roosters" – the others were Wayne Swan and Stephen Smith – who had plotted against Crean in 2003 in an attempt to replace him with Kim Beazley as leader. Latham's comment was not a compliment, but Conroy forever after said he was honoured to be a rooster.

As an ALP frontbencher, he flitted in and out of newspaper headlines for much of the two decades he has been in Parliament, often enough for discomforting reasons.

Much of Conroy's party and political work was behind the scenes. Because of this, suspicion about what he was really up to sometimes became magnified.

As communications minister in 2010, he was assailed by uncomplimentary media reports and commentary after it was discovered he had gone skiing with Seven Network baron Kerry Stokes at Vail Colorado's ritzy Beaver Creek resort, where Stokes owned a $15.5 million penthouse.

The ski-field meeting occurred a month before Conroy reduced licence fees for the Seven, Ten and Nine Networks. Conroy insisted his outing with Stokes had been entirely innocent.

Conroy's career as a minister during the Rudd-Gillard years is most remembered for his role in establishing the National Broadband Network (he was minister for broadband, communications and the digital economy in the first Rudd, first Gillard and second Gillard ministries.

According to political legend, Conroy – unable to pin down then prime minister Rudd to an office appointment – arranged to travel with Rudd on a VIP flight in early 2009. High in the air, he and Rudd are said to have mapped out an early iteration of the NBN on the back of a paper napkin.

Intriguingly, Conroy's latest journey through the headlines – before his sudden resignation on Friday – concerned documents related to the NBN seized from his offices in Melbourne and a staffer's home during raids by the Australian Federal Police.

The documents, allegedly related to an investigation into leaks from the NBN, remain in limbo because Conroy asserted parliamentary privilege, requiring them to be sealed during the recent federal election campaign. Their status remains to be debated by the parliamentary privileges committee.

Meanwhile, only three weeks ago AFP agents raided the Department of Parliamentary Services, which controls Parliament House in Canberra, in quest of the emails of Labor staff members, including those of Conroy.

With all this unresolved, the reasons for the departure of Conroy from Parliament seems likely to remain a matter of conjecture for quite some time, despite his public statements about the chance to spend more time with his daughter.

Born in England, he spent his youth and university years in Canberra, and gained political staff work with the offices of Hawke government science minister Barry Jones and Keating-era sports minister Ros Kelly.

Moving to Melbourne, he served with the Transport Workers Union and Footscray Council before taking, in 1996, the Senate seat left vacant by the retirement of former foreign affairs minister Gareth Evans. He was spotted early as a Labor talent, and within two years was promoted to Labor's frontbench.

He has never left it, despite earning the fury of former opposition leader Crean, who was eventually replaced by Latham in late 2003. Conroy tried to remove from his Victorian seat of Hotham in a factional war 10 years ago, but Crean won back his seat and demanded that Conroy resign as deputy opposition leader of the Senate.

Conroy wouldn't go so easily. When he finally announced his resignation from politics this week, he was deputy leader of the opposition in the Senate.

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