Hello I am a Lawyer with ob er 15 years experience I will try to help you with this.
Do you have an easement over the surrounding land for the passage of the water pipes? Ii there is do you know the terms of the easement? Did the company put their agreement to the work in writing. Were the people laying the pipe going to improve the road or put it back in the condition it had been before the work started and do the Water Co use it too? Qhar do you mean by "tench in electricity"?
I am not sure about an easement, best to assume not. The company said if it was to go ahead the moling under the road would have to be guaranteed for 2 years which Portsmouth Water agreed to comply with. Road would not be improved and pipe is going under road with mole machine so no trench dug. The water company would use the road to read other houses meters and for access to the main water pipe running through the companies field. Another utility company that made a trench in the road, to get their electricty to supply my house with a new cable and then filled it, the company that did this work also works for the company to repair their road, that is why we used them to keep the company happy or try to.
It may well be that the Company are technically wrong to link the 2 issues. Was there an unambiguous agreement in writing (or written confirmation from you to them) to allow the pipes to be laid with no conditions attached. If so then you might well be able to force them to allow the work. However, if there ins't anything clear in writing then the company could easily dispute the existence or nature of any agreement. This could lead to long and costly delays. Is there a reason why you wouldn't want to remove the trees now and then replant them after the pipe has been laid? Your position would be greatly strengthened if you did have an easement. You can checkvonline at http://www.landregistry.gov.uk/public/property-ownership.