For example: where was Conor and what was he doing between the hours of one and three in the morning? He didn’t leave the club. But no one remembers talking to him – or no one admits to remembering, which amounts to the same thing. One theory is that he talked to Laura, but Laura herself maintains that she didn’t even know Conor was in the club until he found her at the exit as the crowd trickled out.

I am left with another mystery. If I had been there, perhaps ... But I was not.

At 2.30 am the nightclub lights came on and everyone groaned at how pale and tired they looked in the sudden glare. People started queuing for their coats. The bouncers started their cacophonous hustling: ‘Move it there, folks, now, please, time to go.’

Time to go.

Questions (always questions): Why didn’t Laura go outside to talk to Richard? Laura herself could never satisfactorily explain this. She was distracted, she said. She was socializing. She was swallowed by the crowd. So why did Richard wait? Why did he sit outside Harry’s for almost four hours, waiting for the club to empty? I know the answer to this question. He was waiting for Laura. He sat and sipped with the same stoical fixity he brought to a solitary session on the rugby pitch. It was in his nature.

At around 2.25 am Barry Fox had come outside to wait with Richard. This was in his nature. By now the hip flask was empty, but Barry had bought a shoulder of vodka earlier that day and now the two of them finished it off.

At 3.05 am Laura made it to the door of the club. She had been separated from Clodagh and Steve in the crush. She stood outside the door and looked around for Richard, but the crowd obscured her view.

Laura hugged herself and felt the grain of gooseflesh on her arms. She took the star-spangled hoodie from her bag and put it on. This was how girls looked at the end of a night out: the glamourous dress half-covered by the homely hoodie.

Outside the nightclub there were girls who had taken off their painful shoes and now stood in bare feet on the edge of the path, signalling for oblivious taxis. Each of the barefoot girls was squired by a teetering young man in a rugby jersey.

At 3.07 am Conor Harris emerged from Harry’s and saw Laura Haines standing by herself.

By now Conor was feeling rakish, and pleasurably drunk. He imagined, I think, that Laura would welcome him in a spirit of camaraderie. He did not, as some people have asserted, ‘leer’ at Laura, nor did he say anything ‘inappropriate’.

Of course, when he said hello to Laura at the door, the time when Conor’s actions made a difference to his fate had already come and gone.

‘Nice hoodie,’ Conor said.

‘Thank you,’ Laura said.

‘You’re welcome,’ Conor said.

Then they spotted Richard, weaving towards them from the other side of the street. When Laura looked for Conor, she found he had disappeared.