Somehow the little scene represented the force of life; the sparrows – almost extinct in my home town of London – were chirping around us, the pigeons were courting their mates, and the strength of springtime sexual attraction was just too strong to withstand. I thought of earlier days in other parks, when I too had practised my karate, and smiled. Later the intern would be made to ring me and apologise, and her voice would read the letter – beautifully – on the half-hour radio programme, as though she were a bereaved mother, rather than a happy-go-lucky student with only one thing on her mind. And all the time I was being interviewed I had to hide the fact that someone had made contact with me, and would almost certainly turn out to be the unknown mother.

A month passed. I received a great deal of mail, most of it electronic, the occasional beautifully calligraphed letter, some even written in purple ink. They fell into different categories. There were those wished to help. A night shift lorry driver sent me detailed graphs about the distribution and popularity of the name Maurice, département by département, decade by decade. A reader ‘with the soul of a detective’ concluded that the mother would have been between thirty and fifty-five years old in 2001. Therefore she would be born between 1946 and 1971; meaning her son would have been born between 1983 and 1988. Using data from INSEE, the National Institute of Statistics and Economic Studies, he concluded that thirty-seven Maurices were born along the northern coasts of France between these dates, and I had only to ask each maternity hospital for their help. ‘Within a few days you will have found her,’ he summarised blithely, surely underestimating the constraints of patient confidentiality.

A couple of readers suggested new and unrealistically time-consuming lines of research that I had failed to explore. The film Message in a Bottle had been sent out a few years earlier as a free sample by a mail order company – perhaps the company could tell me to whom they had sent it? Perhaps Metro could supply a list of their trade suppliers and I could track the bottle through them? Perhaps I could try school registers? Others sent me their theories about how the child had died and why the mother had done what she had done.