I couldn't remember the term used but found it now.
Its an implied Easement which basically means any utility or goverment body or public service can impinge on your property and have a right of access. And they have it until you object to it and get a court order to prevent them.
Its been years since I had any dealings with this but a job I was doing was some fittings for a pumphouse and they need to get in 3 phase and data connection. Three landowners in my opinion got well humped with the power cable and fibre line going in. Absolutely nothing they could do to stop it. They got 100 quid a year per pole on thier ground and 500 quid each for disruption. And if at any point the power cable goes wrong the whole lot will get dug up again.