Paul, there should be no problem with this at all - at least in my experience up here...
Get them to assess the site. Suggest u/g supply to the new property and get the owner to dig the trench and fill it back in. Up here they will change the tranny FOC if it's old enough to warrant it - or a nominal charge if not.
Labour aside, the only expense they will incur is the tranny and cable - no poles. I doubt if they will go for the 'remote cut-out' idea + private cable; but they might.
I recently did a job where the owner got the PMT and the last two 3-wire spans moved from in front of his house ( an old farm ). The 11Kv PMT was reused back 2 spans, they used one new pole, and the last span to the buildings was dropped u/g. It was self-dug. I'm told the total invoice was £5,200.00.
