For the purposes of probate it depends when a person died, the nature of their estate and if they left a will or not.
Before the 11 January 1858, probate was administred by the ecclesiastical courts.
In Wales these were:
- Bangor: 1635 – 1858
- Brecon: 1543 – 1858
- Chester (Welsh wills): 1557 – 1858
- Hawarden: 1554 – 1858
- Llandaf: 1568 – 1857
- St Asaph: 1565 – 1857
- St David’s: 1556 – 1858
The Trefeglwys parish falls under the Diocese of Bangor, and the original documents are now held at the National Library of Wales (NLW). Digital images of these wills are available online, and is searchable here.
For ease of reference, I have listed all the Trefeglwys wills here including a link to the relevant images (held at NLW), a transcription where available and a summary of the key people/places.
After 1858, Probate was administered by the civil courts. An index, also referred to as a Calendar of Grants is searchable. The index which covers Trefeglwys from 1858-1940, is held at the Shropshire Archives. You can also search the Probate Calendar on Ancestry (£).