Right, update.
I really nice chap named Jez @Earwig made me a battery clip for my Avata (and a spare!).
It fits like a glove. No Ace Ventura pun intended. I’m out to test it (with my flying skills tomorrow), but I have tried to remove the battery, ‘with great gusto’, and it doesn’t budge.
Just wanted to thank Jez for a sterling service. Very nice gesture, and what makes GADC what it is.
I’ve included some photos of the ‘Earwig Avata Clip’ attached. In case you can’t make it out, it clips through the rear arms and 'click’s under them. And as a bonus, the clip has cutouts allowing you to power on/off the battery, and see it’s charge LEDs.
Cheers Jez 
