No surprise at all here Grahame.
Let's look at what is likely happening with the software Brian is using and then compare how that would be emulated in a more conventional way.
The process Brian is using resembles the way a traditional HDR image is built up where a number of different images are taken and the software then combines these images into a single image. With HDR we do very much like what Brian has done and take a number of images at different exposures and let the software with its rules combine the various images into one. Based on the rules of the software different parts of each image are selected and used in the final outcome.
In a conventional approach, I cannot see how using a single. global approach could emulate this, so Lightroom is not the appropriate tool to use here. A more reasonable approach would be to use Photoshop and layers and process the individual parts of a well taken image individually; sharpening, adjusting contrast, dodging, burning, etc.
LOCALLY to bring out parts of the image. This is the way that most advanced users approach a single image when they turn it into a final product.
Let me demonstrate with an image I'm about to post. This is a single image shot done at ISO 5600 (i.e. the noise, dynamic range and colour depth are not wonderful). I was shooting as the engine was being moved out of a display building by a shunt engine, so needed a high ISO and was tracking from inside the building to the exterior shot we see here.
Image 1 - Global adjustments only
Image 2 - Local adjustments + Global adjustments (6 adjustment layers + 2 filters)
This screen shot shows the layers I used to come up with the final image (which I need to refine a touch more as I don't like the layer mask used for the sky).