Liam nodded a greeting at the old security guard standing beside the visitor’s book. ‘Hey, Sam, how’s it going?’

‘Whuh?’ The guard scowled at him, bemused. ‘Hang on. How do you know my —?’

‘It’s all right,’ said Liam, grinning, ‘we met a long, long time ago, so.’

Maddy’s eyes rolled behind her glasses. ‘Oh, grow up, Liam,’ she whispered, jabbing him in the ribs and steering him away from the guard, who was still regarding them with an expression that was an even split between surly suspicion and genuine confusion.

‘Last I heard, we were meant to be a top-secret organization … you know?’

‘Aww, he won’t remember. I was dressed as one of ’em Nazi fellas then.’

‘And the timeline was erased,’ added Bob helpfully. ‘The guard will have no memory of the encounter because —’

Maddy raised her hands to shush them. ‘All right, yes … you’re right, Bob.’ She shook her head. ‘Let’s just generally try to be secret, OK? And, while we’re at it, Liam, try to behave like adults here?’

Liam nodded. ‘Aye, you’re right. Sorry.’

‘OK,’ she sniffed, wiping her nose. She’d picked up a cold from somewhere, quite probably the dude who’d been hacking and wheezing over the counter at PizzaLand the other night — giving them a little extra unasked-for topping on their four seasons. She felt like total crud.

‘OK … today’s about learning a bit more history,’ she said snottily. ‘And we can all do with knowing a bit more, but it’s meant to be fun too, right? We could all do with some time out of the arch.’

‘S’right,’ said Sal.