they were developed in Melbourne (Victoria Australia
Not quite - they were developed at the CSIRO agricultural research station at Merbein, about 350 miles from Melbourne.
This institution hybridized or selected several citrus varieties from the Australian native species.
Although there are 'niche' producers of the fruit, they have never become commercially very popular because they are small and not sweet enough to eat fresh.
Sadly, the Merbein site was sold off in 2012 and all their experimental plantings grubbed up.
I was going to visit the Merbein site until I received this email from an Australian contact:
Yes the Merbein CSIRO site was sold and sadly a bulldozer/backhoe was driven over it before it changed hands, probably to protect the intellectual property of the Citrus collection.
I did chat to Steve Sykes about this before the research station closed.
He said the collection was going to be distributed to other sites.
I'm not sure exactly where to, or when or if that happened.
The Australian Govt at the time cut a lot of the research funding budget to CSIRO.
Steve Sykes retired, and I'm not sure if any other scientist took on that type of research into Microcitrus hybrids.
I did see some fruit of 2nd generation Blood Lime type hybrids at a Merbein research field day quite a few years ago, but doubt they will see the light of day now.