Hi Charles
Thank you for your response, my TOC styles aren't based on heading styles they are based on Normal. I think I have found the answer to my problem, trying to re-create my issue I created another document today from a clean MS Normal template document to re-create the TOC from a document with only a heading of each type. I realised in my original Template document I hadn't selected the TOC styles when Limiting Formatting to a Selection of Styles.

Thank you again for your help