To add an external link icon
I.E. When the link is external to your site but still on the .cam.ac.uk domain.
Add the "campl-external" class to the corresponding <a> tag.
E.g. <a class="external-link campl-external" href=".....
To remove an external link icon
Add to ploneCustom.css:
/*remove icons from links to external websites*/
a.campl-external {background: none;padding: 0;}