[1] Coffin was educated at Cowbridge Grammar School and later at a nonconformist academy in Exeter; in 1804 he returned to Wales to join the family business.
In 1791 his father had purchased several farmsteads in the parish of Llantrisant, including the area of Dinas Uchef Farm from William Humphries.
[2] In 1809, at the age of 24 and bored with the tanning industry, Walter Coffin the younger set out to prospect for coal at his father's farm land in Dinas.
[2] Coffin faced four major problems while prospecting for coal in lower Rhondda: there was little known of the geology of the area, there were few skilled miners in the locality, there were no transport links for three miles and there was no proven outside market.
[4] Coffin quickly made arrangements to construct a one-mile tramline to connect his mines in Dinas to that at Griffiths's Denia level and by 1810 the two men entered an agreement ensuring all coal raised in the Lower Rhondda used their interconnecting lines.
Although Bridgend Council found no infringement to planning regulations, the actions caused local resentment to the destruction of "an important historical relic".