Just in case another experience may be useful to others, here is mine:
Our site (barn conversion) has some apparatus that is detailed in and old expired wayleave agreement, and some that isn't detailed the agreement at all. There is a 11Kv pole around 10m from the building and a pole mounted transformer supplying our neighbours' house about 15m from the building.
Quote for connection (which included upgrading the Pole mounted transformer was £17000 if they did all of the work or £12000 if they did only the non contestable work.
I've tried to negotiate a reduced connection price with the DNO in exchange for a wayleave agreement but they have flat out refused, stating that:
"Our connection charges are made in accordance with our Common Connections Charging Methodology and we are unable to accept a partial contribution from our customers with respect to their connection charges. This is to ensure that charges are levied consistently and fairly throughout our distribution area. I am sure you will agree that it is would be unfair for us to use our customers’ money, particularly those in fuel poverty, to partially fund a new electricity connection to your new residential development."
I have tried, at length to persuade them that it will almost certainly be cheaper for them, (and a more economical use of customers' money!) to "do a deal" with me rather than have to go down the necessary wayleave route but they have refused to engage at all, stating that they don't want to set a precedent that other landowners will follow.
The only alternative that they have offered me is £1500 for an easement, which I have declined.
Given the lack of engagement from the D.N.O I served them notice to remove the apparatus back in august, and given Randomiser's experience, I have asked them not to hold my notice period in abeyance because if they won't budge, then I consider negotiations over.
This week, I did receive another email stating that they might be able to reconsider the easement figure by taking into account the open market value of the property in it's current state, but they didn't give me a figure, so it was a fairly meaningless email really......
I hope that my insight may give others an idea of what to expect, and many thanks for the info that I have already gleaned from this thread and from the rest of the forum