Safari is behaving very strangely and changing my code. It seems to happen progressively, so the first edit might be fine, then it all goes horribly wrong.
For example:
& appears
&{assign_variable:template_name="site"}
Quote changed to a semi-colon at the end of this line
{embed="{template_name}/banner;}
Although previous embeds were unaffected
Not sure what is going on but going back to Flock!