Hi David,
Thanks for taking the time to respond. To answer your questions......
I need the full URL as this is for an openGraph meta tag to allow an image to be referenced on something like twitter etc.
SEO/URL settings in both environments are the same, there is only one site and one culture in both environments and UAT has a valid SSL certificate. Locally we are using a self cert SSL.
The input path is coming from a TreeNode object
Tony