She heard her mother tut. “And so on and so forth,” Maria said, her soft Irish lilt exaggerated by the phone’s tiny speaker. “In time, after a lot of technical guff about this old spaceship nobody remembers, I suppose you’ll grope your way back to the point.”

Siobhan suppressed a sigh. “Mother, I’m the Astronomer Royal, and this is the Royal Society. I’m making the keynote speech! ‘Technical guff’ is expected.”

“And you never were very good at analogies, dear.”

“You could be a bit supportive.” She sipped her coffee, taking care not to spill a drop on her best suit. “I mean, look where your little girl is today.” She flicked on her phone’s vision options so her mother could see.

These were the City of London Rooms in the Royal Society’s offices in Carlton Terrace. She was immersed in rich antiquity, with chandeliers overhead and a marble fireplace at her side.

“What a lovely room,” Maria murmured. “You know, we have a lot to thank the Victorians for.”

“The Royal Society is a lot older than the Victorians—”

“There are no chandeliers here, I can tell you,” Maria said. “Nothing but smelly old people, myself included.”

“That’s demographics for you.”

Maria was in Guy’s Hospital, close to London Bridge, only a few hundred meters from Carlton Terrace. She was waiting for an appointment concerning her skin cancers. For people who had grown old under a porous sky it was a common complaint, and Maria was having to queue.

Siobhan heard raised voices in the background. “Is there a problem?”

“A ruckus at the drinks machine,” Maria said. “Somebody’s credit-chip implant has been rejected. People are a bit excitable generally. It’s a funny sort of day, isn’t it? Something to do with the odd sky, maybe.”

Siobhan glanced around. “It’s not much calmer here.” As the start of the conference had approached, she had been grateful to be left alone with her coffee and a chance to run through her notes, even if she had felt duty-bound to call her mother at Guy’s. But now everybody seemed to be crowding at the window, peering out at the odd sky. It was an amusing sight, she supposed, a clutch of internationally renowned scientists jostling like little kids trying to glimpse a pop star. But what were they looking at?