The Barddas
This script which appears in the Barddas, meaning Bardism, a work of two volumes posthumously published in 1862 and 1874, by John Williams ab Ithel (1811-1862) who used fragments of manuscripts left by Edward Williams, better known as Iolo Morganwg (1747-1826), a renowned forger.
In 1856 John Williams had published the Dosparth Ederyn Dafod Aur, also attributable to Iolo. Davod Aur Edeyrn (The Golden Tongued) is said to have written a grammar of the Welsh language around 1270.
The legendary history of the Coelbren script
Einigan Gawr used 3 rods of mountain ash to inscribe God’s name but the people misinterpreted the rods for God himself causing Einigan to die of grief. Afterwards Menw ap y Teirgwaedd recovered the knowledge resulting in the first form of the alphabet consisting of 10 symbols:
Note, the Coelbren letters would only consist of vertical and diagonal lines, as is the case in God’s name. This would make inscription easier on stone and wood. Beli Mawr increased the alphabet to 16 letters:
Then, over time, 8 additional letters were added as indicated in the following diagrams to produce the commonest form of Coelbren which had 24 letters altogether. These additons were made to accomodate for sounds specific to Welsh.
Evidence for the historicity of Coelbren script
It is generally believed that the script was the creation of Iolo as nothing exists that make use of that alphabet. One inscription that speculatively may have evidence for the writing was found near Kenfig in Glamorgan. Although far from being certain, some of the symbols at the bottom look similar to Coelbren letters:
Rev. John Williams wrote of these marks:
Indeed, if these arrow heads had been alone on the stone, I should have considered them most certainly as nothing but the Druidical rays; but then come the other forms on the other angle, to create a difficulty which I cannot get over consistently with this theory.
Arch. Camb. No. Iv 1846,416.