D ale Johnston opens the gate to his neat suburban garden on the western fringes of Newport in South Wales . There’s a trampoline and a slide on the lawn for his grandchildren, and chairs for him and his wife. He should be enjoying the light draining from the perfect autumnal sky – but almost his entire view is blotted out by a vast expanse of prefabricated panels.

The 23 metre-high grey hulk looming over him and his neighbours is a hyperscale datacentre. It is heralded by the area’s Labour politicians as a job creator, yet all Johnston can think about is what he has lost: “Before, the sun used to come around here and it was lovely.” The way residents have been treated is “disgusting”.

Johnston, who used to work for a chemical company in the city, worries what their lives will be like when the centre is switched on: the 36 sets of air blast coolers, needed to stop the chips inside overheating, most likely generate a constant drone, while regular testing of 60 back-up diesel generators, to prevent costly…