I have visited this well three or four times now but never, until now, managed to write down anything about it. I suppose I never fully managed to establish what story there is to tell. Thei accounts of customs associated with Derfel at the site are lengthy, complex and somewhat fantastical but the specific role of the well in these or any other events is either insignificant or largely forgotten.
One of the few early records of their being a well in the parish dedicated to Derfel appears in Edward Lhuyd’s Parochial Queries, a gazetteer compiled in 1698 where he records “Ffynnon Derfel on Garth y Llan close to the church.”
Derfel himself, even when compared to other local saints, has something of a marvellous history. Generally known as Derfel Gadarn (Derfel the mighty), in his early life he was supposed to have been a great warrior, his might and prowess in war were a theme of the medieval Welsh bards. According to one tradition he was one of the seven men who escaped following the battle of Camlan.
It was later in his life that he adopted the religious life founding a community at Llandderfel near Bala; and he is supposed to have ended his life like many local saints at Bardsey Island. 
Prior to the Reformation the customs practised on his wake day, April 5th, revolved around two massive wooden images. One of a knight on horseback the other a stag. These would be carried out onto the field, Bryn Derfel, by the church and would enact hunting scenes in which Derfel featured as the knight.
That Llandderfel was an important site at this time is hinted at through the will of Morgan Herbert in 1526, in which he left provision for his servant to undertake a number of pilgrimages within mid Wales on his behalf, one of the five sites he specifies is Llandderfel at which an offering of 4 pence was to be made. 
Elis Price, Thomas Cromwell’s representative in the St Asaph Diocese wrote to Cromwell in 1538 that
There is an image of Derfel Gadarn within the diocese , in whom the people have so great confidence, hope and trust that they come daily on pilgrimage to him, some with cattle, others with oxen or horses and the rest with money; insomuch that there were five or six hundred pilgrims to a mans estimation that offered to the said image on the fifth day of this present month of April. The innocent people have been sorely allure and enticed to worship the said image inasmuch that there is a common saying as yet amongst them that whosoever will offer anything to the said image of Derfel Gadarn, he has power to fetch him or them that so offer out of hell when they be damned. 
In common with the suppression of such events elsewhere, Cromwell ordered an immediate confiscation of the images and Price wrote to Cromwell again on April 28th 1538 to report that he had removed the image from the church despite the parson and parishioners having offered him £40 not to do so. This might potentially indicate the value of the image to the local community in terms of offerings brought in, and also imply Price was better paid by Cromwell to have refused their offer. 
The figure was sent to London and a month later on May 22nd it was put onto the fire lit to execute the Catholic martyr Friar John Forest, one time confessor to Queen Catherine of Aragon, who had refused to accept Henry VIIIs supremacy as head of the church and was sentenced to burn to death for heresy.. Even this is part of the Derfel legend. It was said that there was a prophecy that Derfel’s image would set a whole forest on fire – the burning of Friar Forest was seen as the proof of the prophecy.
A part of the image however remains in Llandderfel, preserved in the church. Over the centuries it has been worn by use and various attempts to destroy it. The remaining legless and headless wooden animal is claimed variously as either Derfel’s horse or the stag.
The well is some 500 yards to the west of the church on a hillside looking down onto the village. It has been marked and named on every version of the Ordnance survey maps from 1880 to the present day however descriptions of it or records of visits to it appear very few and far between. It was visited in June 1913 on behalf of The Royal Commission on Ancient and Historical Monuments in Wales. Their observer wrote
There is no well at the present time at the spot where the water gushes forth in which adult bathing could have taken place or to which vaticinatory offerings could have been made; there is merely a stone slab about 2 feet long, which, with some rude masonry, protects the spring and forms a small reservoir about 4 feet wide. The water escapes at one side of the stone, and runs along the east side of the field. If bathing or cleansing formed part of the cult of the saint it is difficult to believe that this is Derfel’s original well; it may be, as has frequently happened, that the original watercourse has changed its direction. 
I have been unable to uncover any particular properties of the well or accounts of activity at the well. There was a tradition that at one time water was piped from the spring to a priory close to the church, a small housing estate beside the church is called Maes y Priordy (Priory Field). In the 1850s several earthen pipes were found in fields between the well and the priory area which it was supposed carried water to a large reservoir in the parlour of the priory. Excavations in the 1990s found no evidence of the existence of a priory and there are no written records of it having ever existed.  
Today the spring emerges from beneath a large boulder, there is no apparent sign of the stone slab or any rude masonry referred to 100 years ago in the Royal Commission Report. It lies in a small copse at the top of the field and forms a small pool between the boulder and the roots of a tall tree. I suppose that the flow from the spring at this point is weak since there is no obvious outflow from the spring as noted in 1913. It does, however, appear to re-emerge more strongly 20 or 30 yards to the south, a few feet below a small section of dry stone wall that marks the boundary between the copse and the grazing land beneath it. This output does form the stream on the eastern side of the field reported above. I was unable to determine whether in the last 100 years the ground has changed naturally to divert the stream again or whether the water is now artificially piped to this lower point.
 Baring-Gould S and J Fisher (1908) Lives of the British Saints Volume 2
 Gwynedd Archaeological Trust (1992?) Report on the Archaeological Evaluation at Safle’r Priordy, Llandderfel.
 Jennings R (1861) Llandderfel Parochialia. Archaeologia Cambrensis p76
 Royal Commission on Ancient and Historical Monuments in Wales (1921) – Inventory Volume 6 – Merioneth.
 Thomas, D H (1874) A History of the Diocese of St Asaph
 Hurlock, Kathryn (2018) Medieval Welsh Pilgrimage c1100-1500 Palgrave Macmillan
Ffynnon Dderfel SH 9782 3728