Despite the fame and reputation these endeavors brought to Mayhew, he fell into obscurity in his later years. The events of his life from1865 until his death in 1887 have long been a mystery, but Collection Item 25 reveals that for at least part of that time he was in contact with Geoffrey Hawkins. Item 25 is a letter Mayhew wrote to Hawkins on 22 May, 1880. It was accompanied in the envelope by a what is believed to be the very first documentation of a clock-head.
The text of the letter:
Hawkins was actively pursuing the notorious Dr. Cyncad at this time and at some point had enlisted Henry Mayhew in his efforts. When Archer Bowens forwarded these materials, he noted that it is likely that this was the first time Hawkins and his associates determined a possible link between Cyncad and the clock-heads.