Finally got to the bottom of this. Found a 3D Graphics expert who sorted it all out. I was on the right track but the action needed a lot of work before it would work as a batch command.

Initially I found someone who insisted it needed a script making. The script ended up taking 1.5 to 2 minutes to create each image so this was a non starter. Finally found someone else, far more professional. He created an action with no need for a script and it generates my images in 4 seconds each. I've sent him a number of our mockups (including the excellent clocks from WebTrekker) and he's tweaked the actions to suit them all.

A very small investment that saved me pulling out all of my hair!!