Also, I was already running the Basel Child theme.

I just changed the functions php in the basel child theme folder (in the cPanel file manager section) like you said so it’d include the svg file link (http://sarakirkbyinteriors.com/wp-content/themes/basel/images/SaraKLogo4.svg) – I uploaded this to the images section of the Basel theme (not the child theme).

Should I be doing something else to override the current logo? And should I reload the child theme or will it already take into account I’ve updated the functions php?

Many thanks,
Jack