What's this? Content Control?

I am sat on the train, reading my emails using the Vodafone USB mobile broadband stick, when I get this:

 

My browsing's been censored by Vodafone!  What gives?  I was only looking up a tinyurl pointing to a cycling magazine!  And can I figure out how to change this right now?  No - the relevant website is inaccessible!  One observation is that they are upfront about using the IWF blacklist of sites.