"Bald. Cut mark on head. Scar under right eye, mole left cheek. Lost 4 teeth. Large scar on each side of neck. Cupped both breasts and each side of small of back, hairy chest, cut right wrist. Rupture right side, scar on left groin and inside each thigh, moles on back. Dull hearing".
The reference to cup marks on his chest and the small of his back suggests that he may have suffered physical trauma in childhood, with the various other scars further indicate that he led a somewhat eventful life.
Wilson was a habit and repute thief. The reason why he was in prison when his photograph was taken is revealed by a short report in the Aberdeen Journal of the 29th April 1874,
"John Wilson was charged with theft, on 6th March last, of two shirts, a handkerchief, razor, two scarfs, a leather belt, and a quantity of writing paper and envelopes, from the house of James Farquhar, Richmond Lane, Huntly. The panel is habit and repute, and has been three times convicted before a Sheriff and Jury, viz., once at Inverness and twice at Aberdeen. He pleaded guilty and was sentenced by Lord Deas to Seven Years' Penal Servitude".
The Register of Returned Convicts for Aberdeen shows that Wilson stayed at 7 Justice Lane when he was released on 10th February 1880 (see image below). He remained at this address, which is located just off the Castlegate, until at least November of that year. Although we cannot be 100% certain as to what happened to him after this date, there is a John Wilson of precisely the right age who appears as an inmate of the Old Machar Poorhouse on the 1881 census. If this is indeed "our John", which seems likely, then he was born in Aberdeen in around 1828 and was formerly a linen weaver to trade.