Thanks for the comments folks. Most appreciated.
I only had a short time to take this, so I wasn't as methodical as I should have been.
I had started taking a few shots of the moon, (and failed dismally), but then put the wide on and had a go. I was surprised to see how much it looked like a sunrise shot, so I wasn't really concerned about blowing out the detail in the moon from that point.
As it turns out, I (think I) should have posted this pic instead:
Taken 20 mins earlier, at a far more sensible ISO of 1600, 20 secs at f4. A much better pic overall, I think. No ghost legs, more even light, and no misdirected flashes in the bottom left. Well spotted Greg!
I blame the wine.
I can't recall why I cranked up the ISO in later pics, but I upped the aperture to match too...
I blame the wine. Again!
And, I must ask - are those ghostly little bouncing lights I see you running around with your torch?
Yep. That would be the (red) pilot light on the flash.
Southern Cross is in the middle right of the top of the frame, that is Corvus top left...
You know your stars well. Is Corvus the False Cross?