The implications of DNA and PCR soon became evident. Barry Scheck, later to become even more famous as the DNA expert on O. J. Simpson’s defence team, co-founded the Innocence Project to investigate suspect verdicts. ‘We always knew that there had to be innocent people in jail and that their innocence could be proved through DNA,’ said Scheck. ‘But people didn’t realize then – and still don’t – how amazingly powerful the technology is. Prosecutors, defence lawyers, forensic scientists, let alone the prisoners and their families don’t know . . . that this cup you’re drinking from will have saliva on it, from which DNA can be extracted. They don’t know that you can get it from the sweat on the headband of a hat. They don’t know you can gender-type a bloodstain.’ They probably do by now.

For hair to contain DNA, the root did need to be present. But mitochondrial DNA – mtDNA – was present in all cells, although not in the nuclei, which meant that any cellular material, such as a hair shaft, should contain it. It was this method that had been used in 1994 to check whether Anna Anderson had really been Princess Anastasia Romanov, the last descendant of the Russian Tsar. The ‘highly qualified biologist’ had been wrong. Although there probably was no DNA present in locks of hair, there would be mtDNA, and this was passed from mother to child, or more specifically from mother to son. And, I thought, the locks of hair enclosed with the letter must surely belong to Maurice and his mother.

At this point I decided to contact a forensic scientist to see if this investigative path would lead anywhere. She explained that she did work with hair shafts with no follicles, but that her analysis was done on a comparative basis, she never provided definite answers. In her work at the Forensic Science Service she was sent all the evidence from a scene of crime but this was often no more than a single hair.

There were certain disadvantages with my two locks of hair, she told me. Firstly, the mtDNA would presumably be identical in both samples – unless Maurice was not the biological son of the letter-writer, which seemed unlikely. And secondly, she would not even be able to tell me which lock was from which person. Or even whether they were from two different people. Hair colour was not relevant. ‘My husband, for instance,’ she said to underline the point, ‘has two very blond patches in a darker head of hair.’

Seeing my disappointment, she consoled me by telling me that her true area of speciality was balaclavas, as worn by criminals to hide their faces, and I should really contact a true hair specialist. I grasped at the offered straw.