I bought the two volumes of the "Coin Collectors Manual", 1853, by Humphreys years ago when I was just beginning to develop an interest in numismatic literature. Looking at the price paid, £20 in 1990, it was probably too much.
Inside each one there is a name inscribed in black ink plus a bookplate with the name Edward Jekyll. Curiously this is the name of the doctor in Robert Louis Stevenson's 1886 book "The Strange Case of Doctor Jekyll and Mr Hyde" - but more of that later.
I searched Edward Jekyll on the internet and came up with such a name related to Gertrude Jekyll (1843-1932). She an influential British garden designer, writer, and artist who created over 400 in the UK, Europe and the USA.
Then I came upon a link to an excellent family history website about the Archers, the Goodmans and Associated Families who included the Jekylls. On the page of Jekylls, including Gertrude Jekyll, is reproduced the crest from the bookplate - I had been fortunate enough to track down the right family.
So which Edward Jekyll is it? I'm not sure. It must be either Captain Edward Joseph Hill Jekyll (6 Feb 1804 - 26 Mar 1876) of the Grenadier Guards, father of Gertrude, or his son Captain Edward Joseph Jekyll (18 Aug 1839 - 3 Mar 1921) of the 64th foot, and therefore Getrude's brother. Looking at the membership of the Royal Numismatic Society does not help narrow this search down as the name does not appear to be present on any of the membership lists sadly.
So where is the connection to the horror story? Well Edward jr. and Gertrude had a younger brother, Rev Walter Jekyll, who was a friend of Stevenson and who borrowed the family name for the main character in the book.