Coal was in use before the Romans came to Britain. We can assume coal exposed on the surface was excavated first, and then in an effort to continue working the seam, the first miners had to follow it underground.
Here is a story that is almost certainly true. A caveman gathered sticks to make a fire and rocks to make a fire grate. Some of the rocks were black. When he set fire to the sticks, he was astonished to find that the black rocks were blazing merrily too. He had discovered coal.
We would like to prove this story true with archaeological evidence but we cannot.
There are no clues to the use of coal in the Stone and Bronze ages, nor can we be sure that the Israelites or ancient Egyptians used coal let alone mined it.
We do know, however, that even before the Roman invasion Britons used and mined coal. Flint axes have been found embedded in coal. Doubtless the Romans learned about coal from the Britons - we have evidence of coal stores all along the chilly length of Hadrian's Wall.
At various places along our shores, coal was picked up on beach outcrops. When this was gone, the coal-seekers hacked away at the beach to uncover the seam and follow it inland. If they were lucky, they were able to quarry the coal out on the surface. But generally the seam led them underground. They had to dig in earnest and coal mining began.
Bell pits
The first simple coal mine the bell pit, 'mechanised' with a windlass powered by horses to draw the coal up. We know that monks got their coal this way and we know just how they used it.
Room and pillar
The simple bell pit had hazards, such as 'cave-ins' and failing rocks and earth. So when mining began to develop the first problem to be solved was that of keeping the mine from failing on one's head. The room and pillar mine was the first answer. A bell pit was dug and squared off at the bottom to form a 'room'. Another 'room' was added next to it and another after that. The walls between the 'rooms' were pillars of coal left standing to support the roof. This system was used for centuries. There are many references to such mines from the 13th and 14th centuries on. We know that the mines were lit by rush dips and ventilated and kept as dry as possible.
Photograph of coal mining by hand pick
Longwall mining
One defect of room and pillar mining was its wastefulness because it meant pillars of valuable coal had to be left. The need to get nearly all the coal out led to the introduction of longwall mining, which was common practice from the 17th century onward. A team of miners worked with picks and shovels hewing out the coal on one side of a tunnel in the coal seam called a 'face', erecting timber roof supports as they moved forward. The space behind them was filled with stone waste and spoil - 'goaf'. A road was kept open through the goaf for access to the face.