Thanks Rod, great video

I had to look up what a chechia was!
Quote:
Customs declarations were required. I'm still looking for confirmation that any duty payable could or had to be paid in postage stamps.
I've been doing some more research on this point.
The regulations of the 1886 arrangements with the UK state that customs duties on inwards parcels "must be paid or remitted to the Customs Officer at the Parcels Office, Sydney, before the parcels are delivered or forwarded."
In the 1893 regulations, overseas parcels required a declaration form, stating the contents and value, as well as the address of the sender and addressee, to be completed and attached to the parcel.
As already mentioned, by 1906 customs duty on parcels to the UK could be paid in advance.
In the Cootamundra Herald, 30th April 1892, I found a letter to the editor which stated:

This piece of information leads me to think that customs duty on outwards parcels could be paid using postage stamps. It makes sense, in that the receiving office could see, from the declaration form and the postage stamps on the parcel, that customs duty had been paid.
As for the Burraga piece, the datestamps are Burraga 2nd April 1906 (a Monday) and London 27th May 1906. Burraga was a money order office and the change in classification of post offices appears to have taken place around August 1907, so I'm inclined to think that Burraga would've been classified as an official post office at the time the parcel was sent.
The Orient ship Oruba departed Sydney 7th April 1906 and arrived London 20th May 1906. The P&O ship Victoria departed Sydney 11th April 1906 and arrived London 26th May 1906.
I can't imagine it would be the Oruba as it surely wouldn't have taken 6 or 7 days from landing to get the London Registered datestamp, despite it leaving Sydney 4 days earlier than the Victoria.
The regulations in the 1906 guide say "The department shall use every means to forward parcels to destination as promptly as possible, but it shall not be necessary, in all cases, to forward them by the first mail after posting."
So it looks like possibility 3 is the most likely scenario.