Here is a similar link:
http://internetsupervision.com/scripts/urlcheck/check.aspx?lan=en-US&checkurl=wgtls.co.uk
This one checks the Ladders site from multiple locations around the world, whereas the simpler check probably only tests access from a single location, probably a US one.
The trouble is, inaccessibility may sometimes be restricted to certain geographical locations only, and it appears that's what happened last night. (Accessible in Europe, not everywhere overseas.)
In fact, clicking the above link just now has generated a time-out for Los Angeles, California, while all the other locations including Washington, D.C. and Chicago show OK. (Could well be an error on the test computer in LA.)