Hi Phil,
As mentioned, this is the effect of updated image licensing rules for the developer API tier.
What you're seeing in the article you reference is correct insofar as the only image that is permitted is what is considered the "main" image for the article, and in this case the main image happens to appear in the "main" field, and in top-level elements with relation "main" and "thumbnail", the main block and the main block's elements. This image does not appear in the article's body field, elements or blocks.
Typically an article will have a main image, and this may appear in one or both of the main or body fields, elements and blocks, but only that image will be provided.
The other images that appear in this particular article on the website are different to the main image and are not available to the developer tier under the updated licensing rules.
If you have a requirement for additional images beyond those available to the developer tier, please feel free to reach out to our licensing team through the commercial key request form at
https://open-platform.theguardian.com/access/
Many thanks.