“What’s the threshold number you were talking about?” Arhu said, studying the gate.

“A variable, not a constant,” Rhiow said. “It varies by species. For ehhif, it’s around ten million. For People, eight hundred thousand, give or take a tail.”

Arhu flirted his own tail, a gesture of disbelief. “Where would you get that many People?”

“Right here in this city, for one place,” Rhiow said. “All those ‘pets’, all those ‘strays’—” The words she used were rhao’ehhih’h and aihlhih, ‘human-denned’ and ‘nonaligned’. “There might be as many as a million of us just in this island. Either way, there’s more than enough of us to sustain a gating complex without ehhif being involved … and they’re here too. With such big joint populations, it’s no surprise that this complex is the most senior one in the planet.”

“And besides, there’s the ‘master’ gating connection to the old Downside,” Urruah said. “Every worldgate on the planet has ‘affectional’ connections to it: for all we know, its presence made it possible for all the other gates to spawn.”

Arhu shook his head. “What’s this city, then?”

“London,” Urruah said.

“Don’t tell me … you can smell the local butcher.”

Urruah took a swipe at Rhiow, which she ducked with her whiskers forward, amused to have successfully put a claw into his near-impervious ego. “As it happens,” Urruah said, “I recognize the landscape. That’s Tower Bridge back there.”

Rhiow looked at the bridge between the two towers: it was starting to rise in two pieces, to let a ship past. “Isn’t that the one the ehhif have a rhyme about? It fell down …”

“Wrong bridge. The location it serves started developing gates around the beginning of the last millennium, when the last batch of ehhif with a big empire came through.”

“The ‘Hrromh’ans’.”

“That’s right.”

“Not a very old complex, then?” Rhiow said.