One issue may be the positioning of the master socket - it's in the hallway of his house, with no power socket near it. The cable simply seems to come in from under the house, as there's no obvious cable coming from the junction box at the end of the drive.
There is an extension wired to the master, which goes upstairs and provides ADSL.
When BT installed FTTC at my house, they used my existing extension and mounted the socket in my office, at the end of this extension - that socket is now purely for data, but that's fine.
Any ideas as to what BT are likely to do in my father's situation?