The site has reverted to https protocol again instead of http.
Unfortunately they have left some http script(s) which your browser is blocking, if you allow them you are no worse of than the whole site being http.
It's not blocking for me because of my settings.
Mornings would be a better time to implement changes.
I'm busy with something else but if I get a chance I'll find and post the errant script(s), it's probably a/some script(s) in both http and https.
EDIT
Here you are, sorry for truncated start of some lines and bad formatting but have something else to do
ixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure script 'http://yui.yahooapis.com/combo?2.9.0/build/yuiloader-dom-event/yuiloader-dom-event.js&2.9.0/build/connection/connection-min.js'. This request has been blocked; the content must be served over HTTPS.
vbulletin-core.js?v=423:11 This browser is AJAX compatible
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/style/searchBox.gif'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/style/searchInput.gif'. This content should also be served over HTTPS.
2search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/style/navBG.gif'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/misc/arrow.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/style/navBG.gif'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/misc/navbit-arrow-right.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/misc/black_downward_arrow.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/buttons/newbtn_middle.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/statusicon/forum_old-48.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/statusicon/thread_new-30.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/statusicon/thread_dot-30-right.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/statusicon/thread_hot_new-30.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/statusicon/thread_dot_hot_new-30-right.png'. This content should also be served over HTTPS.
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure image 'http://forum.alzheimers.org.uk/images/styles/Alzheimers/statusicon/thread_dot_new-30-right.png'. This content should also be served over HTTPS.
vbulletin-core.js?v=423:11 Firing System Init
search.php:1 Mixed Content: The page at 'https://forum.alzheimers.org.uk/search.php?searchid=7696204' was loaded over HTTPS, but requested an insecure script 'http://cookie-script.com/s/6caa62d85d3dbf5f38254a2531153fd9.js'. This request has been blocked; the content must be served over HTTPS.
vbulletin-core.js?v=423:11 Fire vB_XHTML_Ready
vbulletin-core.js?v=423:11 Fetch Cookie :: vbulletin_collapse (null)