While some personal possessions become defining symbols (think Tony Abbott's blue ties) others were kept secret (like Bob Hawke's hair dye).

Among the 40,000 items in the Museum of Australian Democracy at Old Parliament House, about 7000 are associated with politicians and about 100 were once owned by prime ministers.

The museum's staff took Fairfax Media deep inside the museum's bunker to see some of the collection.

There are the things you expect like briefcases, stationery, medals and uniforms, but others are more quirky like a pillow belonging to the first Aboriginal MP Neville Bonner.

While some items were donated by families or valued former staff, others were bought at auction.

"Sometimes we're just looking online and something will just pop up for sale and you'll think 'wow'," senior historian Libby Stewart said.

More recently politicians have been known to donate items themselves.

"We've got a large collection over there belonging to a just-retired politician, Christine Milne," she said, motioning towards several plastic storage tubs.

Here staff talk us through some of the highlights formerly owned by six politicians:

1. Senator Dorothy Tangney's champagne bottle "battleaxe". Donated by Tangney's family in 2005. Not on display. Photo: Melissa Adams.

Long before Australia's first female prime minister Julia Gillard was calling out misogyny, one of the first two women to enter Federal Parliament, Western Australian senator Dorothy Tangney was gifted a "battleaxe" in 1944 "to be used as and when required".

"She was launching a ship up in Maryborough, Queensland, with a champagne bottle and obviously the shipbuilder has taken it with all its jagged edges and then very cleverly ... fixed it to an axe handle," Ms Stewart explained.

"This is probably one of almost my all-time favourite objects in the collection."

But the "brutal-looking weapon" was at odds with Dame Tangney's reputation for being "quite a lady" – one of her other possessions in the museum's collection is a lace tablecloth which she took with her everywhere she went.

2. Bob Hawke's hair rinse, laxative, contact lens solution etc. Found by staff in the 1990s. On display in prime ministers' dressing room. Photo: Melissa Adams.

If you're colouring your hair at home most people would do it in the bathroom, but it seems when he was prime minister, Bob Hawke preferred to do it in his dressing room.

Among a bevy of unexpected toiletry treasures, found in a drawer in the prime ministers' office dressing room in the 1990s, were hair rinse, laxatives, contact lens solution, shoe laces and the instruction booklet for an electric shaver.

"Bob Hawke was the last prime minister in this building so we're assuming they were his," manager of content development Kate Armstrong said.

With hair rinse in the shade of "white minx" it's hard to believe they could have belonged to anyone else.

Ms Armstrong said Hawke's "luscious locks" and tanned skin were important parts of his image, so it's "intriguing to think he had to have a little freshen-up".

"[They] give you a certain impression based on media and speeches but sometimes it's actually the really small personal items that can really help you understand the humanity of the person."

3. Robert Menzies' Cinque Ports flag, coat of arms shield, and pennant flag. Donated by Menzies' daughter Heather Henderson in 2001. Not on display. Photos: Melissa Adams.

While Hawke mightn't like the world to know he dyed his hair, another former prime minister Robert Menzies was very proud of his paraphernalia which would later end up in the museum.

Well-known for his devotion to the monarchy, Menzies was rather chuffed with the "spiffy" uniform, flags and shield he received when he was made Lord Warden of the Cinque Ports in 1966 – the first non-Brit and one of only three commoners to receive the honour.

It was a role traditionally in charge of a group of five port towns on the south-east coast of England which provided defence before England had a formal navy.

"All you were really required to do was ceremonial duties and for it you got accommodation at Walmer Castle in the UK," Ms Armstrong said.

"This was really important for Menzies hence the reason these would go straight to the pool room."

4. Edmund Barton's Privy Council bicorn hat. Bought in 2012. On display from June. Photo: Melissa Adams.

Although Edmund Barton's bicorn hat was the same type as Napoleon's, Australia's first prime minister would have been unlikely to have worn it.

Instead, he carried it tucked under his arm much like a "man-bag", content development and commissioning curator Stephanie Pfennigwerth said.

The beaver fur hat with its gold thread and white ostrich feather was part of the elaborate uniform Barton had to wear as a privy councillor whenever he was in the presence of the King until 1910 when the rules changed.

During Barton's time the Privy Council was an advisory committee acting as the High Court of Appeal for the entire British Empire.

It retained the ability to oversee Australian appeals until 1986 and up until the 1970s it was general practice for Australian prime ministers to become councillors.

Barton copped "satirical swipes" for wearing the fancy uniform after cultivating an everyman image when travelling around rural NSW spruiking the concept of federation in the late 1800s.

"A few years later he's prancing around in gold and silk tights, it would have been a bit jarring for people," Ms Pfennigwerth said.

"But he didn't throw the uniform away ... it was important to him and us because it really symbolises Australia's place in the British Empire."

Unlike Menzies' British honour, Barton's status as privy councillor was far from ceremonial and he was far from impressed when a family holiday to London was interrupted when he had to sit on five appeals.

5. Malcolm Fraser's Nareen property sign. Bought in 2015. On display in Prime Ministers of Australia gallery. Photo: Melissa Adams.

Out of context the simple timber routed sign, which once hung on the farm gate of Malcolm and Tamie Fraser's pastoral property Nareen in south-west Victoria, seems of little consequence.

But for a man with a reputation as being a "cashed-up, Collins Street cow cocky", its plainness is symbolic in itself, Ms Pfennigwerth said.

"He was [seen as] a silver tail grazier, someone very wealthy who was totally out of touch with the ordinary Australian ... and Nareen was used as a weapon against him," she said.

"But it was Fraser's sanctuary ... a lot of his personal quirks relate to his farming background."

Indeed his reputation as being "aloof, surly and pompous" could have been attributed to a back injury caused by lifting bags of fertiliser on the farm where he had a very different persona, Ms Pfennigwerth said.

"He use to invite jackaroos and shearers and workers on his farm to Christmas dinner ... he actually had some pretty strong grassroots values," she said.

6. Tony Abbott's blue Hermes silk tie and custom-made Hillbrick bicycle. Donated by Tony Abbott on February 26, 2015. Bike on display in Prime Ministers of Australia gallery. Tie not on display. Photo: Andrew Meares.

Besides his red budgie smugglers, could there be any better way of summing up Tony Abbott than a bike and blue tie?

Abbott rode the carbon-fibre bike for one of his Pollie Pedal charity bike rides and the tie was one of the infamous blue ties Julia Gillard condemned and Abbott defended as part of his "work uniform".

"It's interesting he self-identified [the bike] as something that was important to him," Ms Pfennigwerth said.

"We tend to look for objects that aren't just important because they belonged to a prime minister but something that says a lot about them as a person.

"For some ... due to personality or time or a combination of both, there aren't a lot of physical objects around ... often we're hard-pressed to find something."

Ms Pfennigwerth said ties were heavily laden with symbolism.

Abbott's tie isn't the only one in the collection. There's also a tie owned by Australia's first immigration minister Arthur Calwell who wore black ties every day after the death of his son in 1948 and a collection of hundreds donated by former deputy prime minister Tim Fischer.