So when I run
curl -A Twitterbot http://www.londonnewsonline.co.uk/3583/owner-overjoyed-council-staff-save-90-year-old-tortoise/
The resulting document contains two <html> bodies. There’s a second one at the end, immediately after the embedded stylesheet information. This is not valid HTML. This also happens when I open the page in Chrome, the document is served with two full <html> segments - it’s just the the browser ignores the second one and renders what it can.
I’ve run the same page through the W3C validator at http://validator.w3.org and it lists a large number of errors including the last one which is that having a second document and head is a fatal error.
I do not believe your issue is related to our temporary cards problem. The cards validator cannot read your meta tags as the page is not valid, and the “second” HTML document doesn’t have twitter:card markup.
I’ve not looked at your other site.