‘That narrows it down,’ he proclaimed, clearly trying to console me after the failure of the ESDA machine.

‘What, to people owning a pad?’ ‘Yes,’ he nodded. ‘Maybe sixty billion?’

‘And francophone and female,’ I reminded him. We smiled. ‘Why, I’m nearly there.’

My next move was to ring a specialist ribbon shop, renowned throughout the world. The locks of hair had been tied together with a narrow pale-blue ribbon. The shop I chose was based in London so at least the conversation could be carried out in my mother tongue, although I hung up with the feeling that I had failed to make myself properly understood. But I did manage to establish that they would definitely know all about the ribbon; even though they would never reveal their manufacturing sources, they might be able to supply some useful information. I doubted this, given how the research was going, but if you’re clutching at straws, a ribbon was a satisfactory alternative.

The shop was situated in one of London’s most exclusive neighbourhoods. A little treasure trove of colourful trimmings, ties and decorations, it was packed with ribbon browsers. As soon as I showed the manager the tiny light-blue strip of material he knew the answer with barely a glance. ‘Berisford,’ he said. ‘Manufactured in France. Sold throughout the country.’ He gave it another look. ‘The colour is called Sky, 10mm. Used for christenings, dinner-table settings.’

So there would be no way to track down who had bought it, or rather who had sold it? I persisted. No. Silly question, of course.

By now, the other clients had paused in their perusal of the goods and the shop had fallen very quiet. Some people looked round; others just showed by the set of their shoulders and the stillness of their hands that they were eavesdropping with intent.

I was rather pleased with myself for having discovered the name of the ribbon manufacturer. It turned out that Berisfords was in fact founded in Congleton in Cheshire in 1858 by three brothers, Charles, William and Francis. Congleton was noted as a centre for silk throwing and weaving as early as the 1750s. Purchase by a Swiss company in 1992 had enabled the development of ‘a more European look to its ribbons’. The ribbon investigation was turning into research for research’s sake but I did manage to ascertain that there were numerous French outlets. Perhaps there had been a faint chance that the ribbon was so special that it might have provided some clues, but the straw had turned out, when grasped, to be just that: a straw.

The only other physical element that I had not yet investigated was the pot-pourri of sandalwood shavings in the bottle, but surely that was beyond the call of obsession. It didn’t need a superior shopkeeper to tell me that any analysis of the pot-pourri was time wasted. By now I was beginning to feel very depressed about the whole quest, and starting to wonder whether it was a displacement activity for something missing in my own life. Perhaps I needed to get a job – on a supermarket check-out even – to take my mind off this unsolved mystery.