I dug around in the gift shop. I felt like the only adult in there; the museum’s only other visitors were some Scandinavian tourists, all long legs, backpacks, and blond hair, and a batch of young-teenager schoolkids who seemed to swarm everywhere, their behavior scarcely modified by the yells and yips of their teachers. Eventually I found a slim guidebook to the “Wall Walk,” a tour around the line of the Roman wall. I queued up to pay behind a line of the schoolkids, each of them buying a sweet or a sparkly pencil sharpener or an AMO LONDINIUM mouse pad. An old fart in a duffel coat, I gritted my teeth and stayed patient, reminding myself that all this junk was helping keep the museums free to enter.

Linda found me in the coffee shop. She had come from work; she was an office manager in a solicitor’s office, based on the edge of Soho. She was a little shorter than me, with her hair cut sensibly short, a bit flyaway where it was going to gray. She wore a slightly rumpled blue-black suit. Her face was small, symmetrical, with neat features set off by a petite nose. She had always been beautiful in a gentle, easy-on-the-eye way. But I thought I saw more lines and shadows, and she looked a little stressed, her eyes hollow. She always programmed herself right up to the last minute, as no doubt she had today; she’d have had to make room for me in her schedule.

I bought her a coffee and explained my scheme to do the Wall Walk.

“In shoes like these?”

She was wearing plain-looking flat-soled black leather shoes, the kind I used to call “matron’s shoes,” when I dared. “They’ll do.”

“Not mine. Yours.” I was wearing a pair of my old Hush Puppy slip-ons. “When the hell are you going to get yourself some trainers?”

“The day they go out of fashion.”

She grunted. “You always were perverse. But still—two hours of London roads on a muggy day like this. Why? . . . Oh. This is family stuff again, isn’t it?”

She had always been suspicious of my family, ever since it had become clear that my mother had never really approved of her. “Too dull for your personality,” Mum would say to me. I think Linda had been quietly pleased that I was always remote from them at the best of times, and had drifted even farther from my dad after Mother’s death. We had had enough fights over family issues even so, however. But then we had fights about everything.

“Yes,” I said. “Family stuff. Come on, Linda. Let’s be tourists for once.”

“I suppose we can always go to the pub when it doesn’t work out,” she said.

“There’s always that.”

She stood, briskly gathered up her belongings, checked her cell phone, and led the way out.