You've also forgotten that BT has spent a great deal of time and money in upgrading (and is still doing so) exchanges throughout the country.
Many people do not seem to be aware that BT has technically been a very savvy company for many, many years.
For instance, it worked on the technology and capability 10 years ago to allow checking of service industries' household meters by phone - however, government interference put paid to such plans in case it caused job losses.
Another was video on demand. Again there were objections raised to the scheme from certain sections of the industry in the belief that it would affect their businesses.
The result. The idea was adopted by the Americans and Time-Warner soon conducted successful trials in some US cities and towns.