@Iain Iain 2019, Gimp
I didn’t add sharpening or local contrast, so it looks a bit less contrasty than the others, but I think it’s a very good result. I’m not familiar with this tool, so I’m sure others could do much better; I pretty much yanked up most of the sliders to max. 
I’ve just found there’s a topic for this filter: Test a new noise reduction filter
And there’s another: Preview of my upcoming denoising filter