This culturally significant accessory is a Fountain Pen, 
that once belong to The Honourable Hugh Macrossan (1881-1940) - Deputy Governor of the state of Queensland & a Chief Justice of the state
 
Bearing an engraving "H.D. Macrossan" & dated 20.2.23, 
this pen is an important & fascinating piece of XX century history of Federation Australia 
 
Hugh D. Macrossan was a son of prominent Queensland politician. His parents were both Irish immigrants, married in Australia. 
After graduation, H. Macrossan worked as a teacher, before becoming a politician & being elected as a member of Queensland Parliament.
He served as a judge (from 1926) until his appointment as Chief Justice in 1940.
 
Refer to the link -  https://www.sclqld.org.au/judicial-papers/judicial-profiles/profiles/hdmacrossan  - for further details relating to biography of this prominent figure.
 
Pen is crafted in 9K Solid Gold & features a solid gold Nib, signed "DeLaRue, Onoto"
 
Bearing English Hallmarks: 
London (leopard head)
Letter date - 1912
375 - 9K gold 
 
Total item's weight: 21.6gr
 
In great vintage condition 
Comes in original antique box - a perfect place to store it 
signed "Onoto"