http://huaweihg612hacking.wordpress.com/about/
BT own the monopoly on the copper infrastructure and they are the only company providing high speed ADSL. If you want 80Mbps broadband, you have no choice but to use the Huawei modem.
The device is reasonably hackable (and, in fairness, complies with its open source obligations http://www.huaweidevice.com/worldwide/technicaIndex.do?metho...) - but there's no real way of knowing what secrets the silicon holds.
So, the UK has sold off the line equipment, monitoring filters, and mobile infrastructure to one company. What could possibly go wrong?