I want to have the pages on my monolingual UK-based site optimally set up. Currently I am using <html lang="en-gb"> on each page. I understand that Google not longer looks at this property and instead only pays attention to hreflang. Is hreflang only relevant on multilingual web sites? I looked at Bing who state to primarily use <meta http-equiv="content-language" content="en-us"> but otherwise use the html header as above. Is it best to just stick to html lang or is content-language a better option? https://blogs.bing.com/webmaster/2011/03/01/how-to-tell-bing-your-websites-country-and-language/