The same process even applies to the provision of basic phone services. Whilst the supply of a copper pair is covered by a USO for a fixed cost, that's only up to a reasonable cost. (Which I seem to recall was deemed to be about 10 man-days of cost). Beyond that it's covered by excess construction costs.

One little bit of regulatory detail is that BT are not allowed to include excess construction costs as part of their capital exp[expenditure for the purposes of earning a regulated return.

nb. you can also get hit be these sort of costs (or worse) if you need to connect up to other utilities if excessive costs are involved. People seem to forget that broadband is a new utility. It just happens to be fortuitous that for many an acceptable service can be achieved over lines originally laid for phone services.

you can also get hit be these sort of costs (or worse) if you need to connect up to other utilities

One of my colleagues was quoted about £18K for installing gas to their property - the gas line runs to the newer houses to the rear of the property but has never been run to the older houses.