The Book of Ballymote became O’Gorman’s property when he purchased it for £20 from a millwright’s widow in Drogheda.
O’Gorman deciphered the Ogham script and translated it. He asked Gabriel Beranger, a Dutch artist interested in illustrating Irish antiquities, to copy some of its illustrations. He left it with Cathal Ó Conchobhair of Belanagare (The O’Conor Don), the leading expert on Irish manuscripts, who determined it was written under the patronage of Timothy Mac Donogh, chief of Tir-Olioll, Artagh, and was transcribed about A.D. 1390, when Torlogh O’Connor was King of Connaught. It was purchased from the Mac Donoghs of Coran by Hugh Duff Ó Donell, Prince of Tirconnell in 1522, at the price of 140 milch cows.