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Well you're on Wordpress and are using YoastSEO. When a Wordpress category is created, a URL is generated for that category. Your sitemap was created with Yoast: Sitemap Last Modified | https://tipbox.abcam.com/post-sitemap.xml | 2018-08-23 08:10 +01:00 https://tipbox.abcam.com/page-sitemap.xml | 2018-08-23 08:21 +01:00 https://tipbox.abcam.com/attachment-sitemap.xml | 2018-08-23 08:08 +01:00 https://tipbox.abcam.com/life_work-sitemap.xml | 2018-08-07 10:40 +01:00 https://tipbox.abcam.com/category-sitemap.xml | 2018-08-23 08:10 +01:00 https://tipbox.abcam.com/author-sitemap.xml | 2018-08-23 08:13 +01:00 | I can see your articles are indexed now, but I would still recommend removing the Wordpress category URL's from your sitemap. Since the sitemap is commonly used for the things you want Google to crawl and index, I would add the article urls and content with "index,follow" webpages directly to your xml sitemap instead of linking the category pages you don't want indexed. (IE: ie: http://www.genetex.com/sitemap.xml) Yoast should give you this option in the settings for xml sitemap generation. If not, I would recommend using Screaming Frog to generate the sitemap.

Thanks for this - definitely some food for thought regarding how we handle 404s in general... I am more worried about search engines than humans from this type of thing (we have had no referrals from this dodgy site) so would be interested to see if you still think a 301 is the best way to go since the link text may not be appropriate to our site (and perhaps this would be worse?!).