Hi. Thanks for quick reply.
Initially I added the new file in the parent theme, but nothing appeared in list of skins.
I’ve now also tried recreating in the child theme (By replicating structure) and editing an existing skin css. (I copied the yellow.css from parent to child and made an edit in the child folder). This doesn’t seem to change the skin on the live website. I would guess it is using skin css file from the parent, rather than child.
I haven’t yet edited the css in the parent theme.