Thanks for your suggestions.
At first I would have agreed that it was a lighting issue, the two renders certainly do look different on different machines, but I've looked into it further...
The item that isn't rendering correctly is a linked block
Opening the block file on the computer causing issues, when rendered it comes out fine (attached).
Also, if I explode the block in the model, it renders fine also (comparison renders all attached).
All attachments were done on the same machine without changing any settings in between (just exploded the block).