There being no mandate as touted, nor is there ant justification to site the Cullen report etc. NR may just want to place a mast at Calstock for 'better' communication with the driver or workmen that may visit the site.

So the question of costs is an issue. That they may have already laid optic fibre at some expense, is no excuse to spend more on a 95ft mast to exploit it. It may well be someone's pet project that they were well paid to design, and they, or their successors in title would like to the fruits of their labour.

Costs:

Mast Installation
Running cost; Daily electricity.
Maintenance
Life expectancy