Thanks all.
I'd just assumed that RAAF Edinburgh was some sort of centre of excellence for electronic warfare, and that the rationale was to co-locate those operating the Tritons with other similar ELINT, SIGINT type specialists that worked on Jindalee.
Much more mundane and practical reason by the sounds of things.
As a kiwi now resident here, you're much luckier than the poor old RNZAF.
They could do with a Triton or four as well.
Took a ride with the guys on 5 squadron once - they do a great job. I think they're lobbying Wellington for the Triton as well, but its a pricey platform...