Peter this is in the Biome at the eden project. I have not a clue about artificial light such as flashes and diffusers. I stick an old plastic see through bottle over a flash on the very rare occasions I use a flash and hope for a good mistake.
These Biomes being of a steel structure with plastic , this plastic does as I have found give superb clarity and subtle lighting.
It maybe it is designed this way or just a nice accident that the translucency of the plastic works for photography.