Test

This is just a test of Chris Jepson's recommended technique, poorly and hastily carried out.
Paul, I have the same flashgun as you. I have ordered a radio trigger - mine is for Lumix G9 (and Olympus).I found a YouTube video on using the flash off-camera without a trigger, but it doesn't work for me. You have to set the flash to manual and in your camera turn off automatic flash. In the G9 you can't change the flash settings unless there is a flash on the camera. (The Olympus come with a little flash you can attach - but I don't know how it is with the Fuji) 
https://www.youtube.com/watch?v=pbBSXxfqUJs
I set my camera on a 2-second shot and fired the flash manually. 
I know the background isn't very black but I will try again when I get the trigger. 
Thanks for the method, Chris!