Sorry if people have had issues with the 404 page behaving oddly of late…
It seems it was a problem with a bug with the way 404 pages for WordPress work on the Fasthosts servers (it causes only some of the page to be displayed). However, we found a fix, which is a very strange solution – and as there doesn’t seem to be a solution out there in Google-land I’ve posted it here incase it helps save people a hours of their life!
In the end I found that if I add 7,889 extra characters (just random letters) to the beginning of the 404.php file, then it works fine! It seems that the issue on the Fasthosts servers means that it is ignoring the first 7,889 characters in the file! So just filling those characters with rubbish means that when it gets read in, it misses out that amount of letters, leaving the rest of your correct code.
Odd stuff… But bloody glad it’s now working!