A collection of fifty of the poems of Ieuan Deulwyn were published in 1909 under the auspices of the Bangor Welsh Manuscripts Society, thanks to Ifor Williams.
Because they have similar styles, their work is constantly attributed to each other, which makes definitive identification of Ieuan's poetry difficult.
But, as Glanmor Williams says, “Far from being fetters which intolerably shackle the poet’s ability to express himself freely, [the rules of cynghanedd and cywydd] become adornments which add to the power as well as the elegance of the verse”.
Williams says that he is “above all a poet of love.” And George Borrow opines that “Ieuan Deulwyn’s most beautiful production is his cywydd to a birch tree.” Borrow suggests this might have some relation to the “deulwyn” part of his name,[4] but the word for birch, bedwen, can also mean a symbol of constancy in love.
Similarly, in his elegy to Dafydd Fychan and Ieuan ap Gruffydd: “As Mary mourned, beneath the cross, her son’s fell wounds, so I their loss.” His poems of praise are loaded with genealogy, “until they bore the poet,” but they are a treat for the historian and genealogist.
He was a contemporary of Lewys Glyn Cothi, and they frequently wrote of the same people, with the benefit that one poet often supplements the other in clarifying relations of local families.
That the name is Elizabeth is clarified by Gervase Bushe in his entry at June Ferguson's Royal Genealogy Page Elen married Hywel ap Maredudd of Cromlech, Llanfechell, Anglesey, and a fairly extensive list of at least one line of her descendants is documented.
Other descendants of Ieuan Deulwyn remained in Carmarthenshire, as evidenced by a 1609 survey of freeholders in the Welshry of Kidwelly.
As a descendant of Cadwgan Fawr, Ieuan was a distant cousin to his neighbour Gruffydd Dwnn,[19] with whom he may have served in the French Wars in the first half of the 15th century.
[20] Howell Evans attributes poetry written to the Welsh hero Mathew Gough to Ieuan Deulwyn.
Ieuan Deulwyn's name appears in a 1460 commission attributed to Edward IV to look into the lineage of the Herberts, in which the poet is said to be one of the four 'cheyffest men of skill within the provynce of Sowth Wallys,' presumably in regard to genealogy.
He is styled a “fervent supporter to the men of York” by his editor, Ifor Williams, but a closer look at the subjects of his poems reveals that his devotion is more to family and country than to a political faction.
He criticized Bedo Brwynllys for playing it both ways with regards to the political factions, yet Ieuan himself composed poetry for both Lancastrians and Yorkists, as can be seen graphically in the accompanying figure.
As Evans writes, referring to the bards of the 15th century: “They sing the glory of a Tudor or a Herbert according as each rises to eminence, and bids fair to become a national leader.
In his poem, "I Ferch a'i Gwallt" (To a Woman and Her Hair), Ieuan suggests half-jokingly, that his love should not love him more than a “deceitful Englishman.” And in his elegy to Sir Richard Herbert, Ieuan refers to the English as the children of Alis, which the Reverend Ellis notes means the children of Hell.
[24] Sir Richard Herbert of Coldbrook, near Abergavenny, was Ieuan's principal patron, but he was in the homes of many of the most influential figures in South Wales.
He alludes to the stature of her family: Her father is like Hu Gadarn [a figure from the Mabinogion]; Great is his concern about a husband for his daughter.
Her father was Thomas Rede, a merchant who was connected with some of the most influential families in South Wales, and her mother (or at least step-mother), was Elen, daughter of the powerful Gruffudd ap Nicholas.
His wife's cousin, Sir Rhys ap Thomas, played an important role in the battle, which led to him being knighted on the field.
Ieuan knew Rhys ap Thomas well, and sang his praises, but there is no mention of his exploits at Bosworth.