In each hotel, Robertson had a special underground safe room stocked with enough food and water and entertainment for six months, and he had a cache of weapons in each safe room for his own protection.
In 2018, Robertson had a hotel built in Sheffield on top of a disused and abandoned coal mine. It was located just north of Parkwood Springs, south-east of Shirecliffe and south-west of Longley Estate. The mine system had been transformed into a landfill which Robertson was aware about. He was also aware of the landfill's toxic waste materials that hadn't been disposed of, but he ignored it in favour of opening the hotel.
Unknown to Robertson and his people, the toxic waste contained dead carcasses of giant spiders from Sheffield Hallam University, including one that wasn't completely dead. It grew larger, feeding on the toxic waste until it was so large it eventually found itself suffocating. The mother spider led a number of giant spiders which had also fed on the waste and had become larger.
Robertson later shot the mother spider, ignoring the fact the creature was already dying.
Najia Khan briefly worked as a general manager at the Sheffield hotel, but she was fired by Robertson when she walked in on the businessman speaking to one of his employees, Frankie Ellish, who was worried about the landfill. He later fired her again (which he technically didn't as he couldn't fire someone again without retiring them) when he saw the cobwebs left by the giant spiders in the bedrooms. (TV: Arachnids in the UK)