Hey there sarahduncanprint,
How are you doing today?
I’m not being able to open your site, generally this should be possible with some custom CSS.
You should be able to target single post pages that are using image post format and remove featured image only on those pages.
I’ve tested this on my end so hopefully it will work on your site as well. Try adding the following CSS code in the style.css file of your child theme or add it in your site using the following plugin:
http://wordpress.org/plugins/simple-custom-css
.single.single-format-image .portfolio-image {
display: none;
}
Hope this helps 🙂
Cheers,
Bojan
brilliant, many thanks Bojan