Hi Bron - this may well be a Tau Emerald, but in its teneral state there is insufficient clarity to be certain, and the dorsal extensions of the lateral markings on abdominal segments 7 and 8 could suggest an Australian Emerald. I've created a taxon for Hemicordulia sp. for this one (and any others that prove impossible to distinguish between the two). Sorry I couldn't be more specific.
Thanks Harvey. I enjoy and learn from comments from those who have extensive knowledge (as you do) and are prepared to share their expertise freely . Much appreciated. :)