Your question has to dimension to take into consideration.
- handling multiple languages
- handling duplicates
Handling multiple languages
Organizing language versions in subdirectories is a good strategy. For me it is best practise.
If you are able to identify which language/country your user is looking for redirect him to the right directory.
If not - lead him to your global start page. That is fine so far.
If you visit www.example.com it will redirect you to either
www.example.com/uk or www.example.com/ie or www.example.com/global.
That's fine.
Handling multiple languages for different search engines:
Google and Yandex are using hreflang as a guide to multilanguage pages.
https://support.google.com/webmasters/answer/189077?hl=en
https://help.yandex.com/webmaster/yandex-indexing/localized-markup.xml
A sample configuration for your page may look like this:
<link rel="alternate" href="http://example.com/ie" hreflang="en-ie" />
<link rel="alternate" href="http://example.com/uk" hreflang="en-gb" />
<link rel="alternate" href="http://example.com/global" hreflang="x-default" />
Always make sure your hreflang is also self-referential!
Bing uses language meta-tags.
http://blogs.bing.com/webmaster/2011/03/01/how-to-tell-bing-your-websites-country-and-language/
A sample configuration for example.com/uk may look like this:
<meta http-equiv=”content-language” content=”en-uk”>
You can check for language detection in the search engine's own web master tools:
Google: https://www.google.com/webmasters/tools/
Yandex: https://webmaster.yandex.com/
Bing: http://www.bing.com/toolbox/webmaster
Handling page duplicates
By always redirecting to one of your language directories you handle the duplicate example.com
and example.com/global
fine.
Make sure you are always using a 301
redirect. Then there is no problem for your homepage being redirected to a subdirectory. Depending on the location a web crawler visits your page it always is redirected to the right version of your page. Indexing the example.com
duplicate is omitted.
As you said:
This is OK, and incidentally is how The Guardian newspaper works.
It works.
If your web server accepts URLs that do not contain a language directory like example.com/topics/article-01
make sure those get either redirected to their equivalent version (f.e example.com/global/topics/article-01
) or have a canonical link element pointing to their equivalent.