Thanks Frank
I've had a look at the HTML source when Visual Composer Frontend Editor starts to load and there are no links to AO. But I'm guessing VC loads on top of the page as when I enable Developer Tools in Chrome I see two errors -
1) Uncaught SyntaxError: Unexpected token % in autoptimize_6d7....js:5
2) Uncaught TypeError: vc.frame_window.jQuery is not a function in shortcodes_builder.js:71
Hopefully this may throw some light on the issue.
Thanks
Peter