Jerusalem also refers to Daleks, which are as much a part of the British landscape as the supermarkets that Alan Moore names, and, again, Moore has contributed to that fictional universe. The Daleks are enemies of the Time Lord known as the Doctor and Moore wrote back-up stories about other Time Lords in Doctor Who Magazine.
The BBC's the Doctor and the Daleks are successors of HG Wells' the Time Traveler and the Morlocks. Wells incorporated an ironic reference to Morlocks in one of his mainstream novels:
"There's an incurable misunderstanding between the modern employer and
the modern employed," the chief labour spokesman said, speaking in a
broad accent that completely hid from him and the bishop and every one
the fact that he was by far the best-read man of the party. "Disraeli
called them the Two Nations, but that was long ago. Now it's a case of
two species. Machinery has made them into different species. The
employer lives away from his work-people, marries a wife foreign, out of
a county family or suchlike, trains his children from their very birth
in a different manner. Why, the growth curve is different for the two
species. They haven't even a common speech between them. One looks east
and the other looks west. How can you expect them to agree? Of course
they won't agree. We've got to fight it out. They say we're their
slaves for ever. Have you ever read Lady Bell's 'At the Works'? A
well-intentioned woman, but she gives the whole thing away. We
say, No! It's our sort and not your sort. We'll do without you. We'll
get a little more education and then we'll do without you. We're
pressing for all we can get, and when we've got that we'll take breath
and press for more. We're the Morlocks. Coming up. It isn't our fault that we've differentiated."
-copied from here.