Thank you Ty Gwyn - I appreciate your comment.
Phil Cullen's write up is not incorrect as Pant Hywel was initially developed during one of the periods that Stradey Level was disused and, as Stradey level had worked far towards the crop, Pant Hywel was indeed partly working Stradey Level pillars. Subsequently, after the two sets of works were connected and Stradely Level recommenced work, Stradey Level seems to have formally designated one of the Pant Hywel slants as an airway. The area was worked for coal, reworked for coal and clay, and further reworked mainly for clay. Various entries (mainly slants) on the crop operated intermittently during times that levels and pits at the base of the hill intermittently worked. The complexities of which entries reworked which older entries' old workings is well-nigh impossible to fully untangle as there is incomplete plan coverage, especially for much of the pre-twentieth century workings.
As far as I have been able to work out, Pant Hywel initially (1906-15 when owned by Joseph Evans & Brothers of Pwll, trading as Pant Howell Colliery Co) worked old Stradey Level nineteenth century pillars near outcrop from a level or slant at SN 487 015, draining their workings via Stradey Level - and almost certainly also using Stradey Level as an airway as the c.150 ft. altitude difference would have provided an efective natural ventialtion current. The slant used by Messrs. Evans was the uphill exit to the Llanelly Colliery Company's underground tramway of 1897. After Messrs Evans sold Pant Hywel to D.J.Griffiths of Cross hands in 1916, the new owners drove a new level or slant at SN 481 016 (driven simultaneously from both surface and from the extremity of Evanses' workings underground) to work a different area of Stradey Level nineteenth century pillars, and again used Stradey Level for drainage and, undoubtedly,ventilation also. It was this slant of c.1917 that was in use at the time of abandonment in 1925. Both the Evanses' and Griffiths's enterprises were very small scale, emplopying around a dozen men underground and one on surface (undoubtedly the winding engine driver). Two years after the Evanses had begun work, David Jones had built Stradey Brickworks and reopened Stradey Level to supply it with clay and coal. After Pant Hywel was abandoned in 1925, David Jones and later his son and successors, worked Stradey Level for a further forty years, seemingly to at least partly re-work a portion of Pant Hywel workingsto extract underclay as the Evanses and Griffoihs had concentrated on coal in pillars and seem to have ignored the clay. David Jones rarely employed more than half a dozen men underground and often fewer.
The portal of Stradey Level was originally, during its early and mid nineteenth century working, at SN 487 012, at the foot of the hill-slope. During its period of abandonment, from the mid nineteenth century to 1897, what is now referred to as Stradey Home Farm was built on the lefel land immediately south of the base of the hill. When the Llanelly Colliery Company reopned Stradey Level in 1897 they were obliged to construct a few hundred feet of shallow cut-and-cover tunnel to extend Stradey Level by about 100 yds to the south, beneath the Home Farm, with a new portal at SN 487 011. It is this latter portal that is shown in the photograph and on the 1960s film.
There is one error in my post of yesterday - the 1897 standard gauge siding (known at the time as the Marsh Railway) connected to the Stradey Estate Private Railway, not to the Llanelly & Mynydd Mawr Railway. Slight earthworks (the groundd it traversed was almost flat) and a substantial masonry bridge over the Nant Trebeddrod survived on the course of the Marsh Railway until the 1980s. Across one field the impressions of the wooden sleepers remained perfectly clear, from c.1901 when the track was lifted an sold following the collapse of the Llanelly Colliery Company - rather remarkable. given that eighty years had elapsed and that this was a heavily industrialised area.