[prawn]

And AFAIK the caching will run for about 30 days unless you clear it manually or through the API. Might be different for major sites.

[jonah]

Yeah, it caches the preview.

As mentioned in that doc, you can use the URL Debugger[1] to see the Open Graph data and even clear the cache.

I cleared the cache for the OP's BBC URL, try sharing it again and see what info you get.

[1] https://developers.facebook.com/tools/debug/