By the time she’d taken the dirty dishes through to the sink, Grant was at her intercom. She checked anyway that it was him, then pressed the button to let him into the tenement. She was standing by the open door when he hauled himself up the last few steps.

‘Sorry it’s so late,’ he said, ‘but I couldn’t keep it to myself.’

‘Coffee?’ she asked, closing the door after him.

‘Thanks. Two sugars.’

They took the coffees into the living room. ‘Nice place,’ he said.

‘I like it.’

He sat down next to her on the sofa and placed his coffee mug on the table. Then he reached into his jacket pocket and pulled out a London A–Z.

‘London?’ she said.

‘I went through all the kings I could think of from history, then anything else to do with the word king.’ He held up the book so its back cover was showing. A map of the London Underground.

‘King’s Cross?’ she guessed.

He nodded. ‘Take a look.’

She took the book from him. He could hardly sit still in his seat.

‘Seven fins high is king,’ he said.

‘And you think the king is King’s Cross?’

He slid across the sofa, his finger tracing the light blue line which went through the station. ‘Do you see?’ he said.

‘No,’ she said grimly. ‘So you’d better tell me.’

‘Go one stop north of King’s Cross.’

‘Highbury and Islington?’

‘And again.’

‘Finsbury Park … then Seven Sisters.’

‘Now backwards,’ he said. He was practically bouncing on the spot.

‘Don’t wet yourself,’ she said. Then she looked at the map again. ‘Seven Sisters … Finsbury Park … Highbury and Islington … King’s Cross.’ And saw it. The exact same sequence, but abbreviated. ‘Seven … Fins … High Is … King.’ She looked at Grant. He was nodding. ‘Well done you,’ she added, meaning it. Grant leaned over and gave her a hug, which she squirmed out of. Then he leaped from the sofa and clapped his hands together.

‘I couldn’t believe it myself,’ he said. ‘The way it just suddenly screamed at me. It’s the Victoria Line.’

She nodded, couldn’t think of anything to say. It was indeed a section of London Underground’s Victoria Line.

‘But what does it mean?’ she said at last.

He sat down again, leaning forward, elbows on knees. ‘That’s what we have to work out next.’

She slid across the sofa a little, making some space between them, then lifted her pad and read from it. ‘“This queen dines well before the bust.”’ She looked at him, but he just shrugged.

‘Could the answer be in London?’ she asked.

‘I don’t know,’ he said. ‘Buckingham Palace? Queen’s Park Rangers?’ He shrugged. ‘Could be London.’

‘All these Underground stops … what do they mean?’

‘They’re all on the Victoria Line,’ was all he could think to say. Then they stared at one another.

‘Queen Victoria,’ they said in unison.