Since June 2004 the University's proxy servers have defaulted to block some forms of advertising. This was initially done to save Internet bandwidth, and more recently was perpetuated because of the presumption that users prefer fewer adverts when viewing web pages.
The way advertisers use the web has changed, and these centralised blocks are no longer as effective as they once were. In addition, web browsers have evolved to make it significantly easier for users to perform advert blocking within their own browser using plugins or extensions. (A widely used example of this sort of thing is Adblock Plus). Putting ad blocking into individual browsers gives users significantly more control over what they see on the web, and exactly what gets blocked.
For these reasons, we intend to discontinue advert blocking on the University's proxy servers during the 2 February maintenance window.
You will not need to reconfigure your browser in any way as a result of these changes. All existing, supported configurations will continue to work.
If you wish, you can immediately see the effects of doing this by using the existing opt-out mechanisms.