Site menu highlighting

I am trying to get my site menu to work but am having a problem finding a condition that will uniquely identify the blog page. I have used is_home() for the home page, is_page(‘about’) for the about page etc but the blog posts page seems to be neither a page, nor a post.

My site can be found at https://johnhobsonphotography.co.uk/

Could anyone suggest a conditional that I could use?

thanks
John