I cannot help with the Uniform, but I do know the surname PITTAR in that era in Sydney ... only from a local history aspect, not family ... although I can wish ! and I am sure Les can too ... Kirribilli House ...
Hopefully the following is NOT too much of a side track. I noticed the surname PITTAR and my local history knowledge said ‘Kirribilli House’ … which of course is the Sydney Residence for Australian Prime Ministers… so I have been thinking outside the square …. Anyways …
Arthur Thomas Henry PITTAR, the dentist, likely also owned various properties in Darlinghurst. Perhaps including the famous Hampton Court Flats. SMH 11 July 1941 has the family notice with names of his wife and children.
https://trove.nla.gov.au/newspaper/article/17752626 Likely some of the funding to construct those flats may have come from the deceased estate of Walter Douglas Brewer PITTAR, dentist… who died 1922… Govt Gazette 1 June 1923
https://trove.nla.gov.au/newspaper/article/225019624 (and some funding from sale of Kirribilli House to the Commonwealth too) …
Govt Gaz 6 Feb 1903, p 1056 has 3 dentists PITTAR … all from Auckland: Arthur Thomas Henry, Parke, Walter Douglas.
https://trove.nla.gov.au/newspaper/article/220260359/14061243 Same 3 Govt Gaz 28 Jan 1909 p 496.
https://trove.nla.gov.au/newspaper/article/227059309/14941327 Looking at NZ BDM Parke has children in NZ 1900, 01, 03, 05, 07, 09, 13; Walter in 1905 and 1908, and Arthur in 1900, 02, and 07. Mary Ann PITTAR dies in New Zealand, aged 39 years, in 1909. And then in NSW Arthur marries Catherine Morgan in 1912. Arthur and Mary Ann also have children in NSW …
Now, I think Arthur was likely known as ‘Harry’ …. See the Auckland Star newspaper, 13 Dec 1909. Two brothers (both married at the time) are setting out to conquer London with Dental Chambers … They arrived six months prior (probably per the SS Malwa ex Sydney early April, - arriving London 8 May 1909) … then in December 1909, NZ papers past news item shows that Harry PITTAR had a recent loss, and needed to make ‘flying visit’ to NZ via Marseilles and Sydney.
https://paperspast.natlib.govt.nz/newspapers/AS19091213.2.37 I may be way off track, Les, but I am confident that Kirribilli House (the Sydney Residence for Australian Prime Ministers) was once owned by Harry PITTAR, the dentist.
JM
ADD
dob for Herbert seems to be early August 1909.

drilling down on NSW BDM online index.