Just to follow up from my post earlier, we are having exactly the same problem with ITV, CH4, Amazon Prime etc, so this does not look to be purely a BBC problem. Can anyone else try a few different sites to test that I am not alone in this please. BBC seem to be suggesting that because traffic is routed via a proxy server they cannot guarantee that the site is UK based despite the IP being registered, which would suggest the issue lies with schoolsbroadband.
Just to prove a point, I have an external router in my office to test staff Direct Access connections on their domain joined laptops. If I log on to our domain using this external route, all of the links we are having UK based issues with in school play perfectly, so come on schoolsbroadband, this is almost as big an issue for schools as the recent filtering debacle.