Hiram Baylis's memorial stone was removed about 15 or 20 years ago and not in the 1970's. I found it whilst looking for miners who were killed in the Forest of Dean. Unfortunately I did not take a photo when I should have done.
Attached below is a copy of the Gloucester Journal report of the accident. The inquest will have to be attached in another listing as it is all too large.

Plump Hill Explosion

Gloucester Journal, Saturday,22nd June 1872

Rock Blasting at Plump Hill- death of four men.

For some time past, preparations have been made by the owner of an extensive limestone quarry, named Symonds, to blast a mass of valuable limestone, at the Plump Hill, Mitcheldean, with a ton of gunpowder, and fears were excited for the safety of the district. Applications were made both to the local justices and guardians to prevent the explosion, inasmuch as the immediate locality was dotted with dwellings, but it was stated that they could not interfere. On Monday night the powder was successfully fired, many persons having assembled near to witness the explosion, of which the following account is furnished to us by a spectator:-

Although expecting many to be present, I confess that the numbers far exceeded my anticipations. Six o’clock was the hour named for the blast, but before that period arrived numerous groups had posted themselves on the hill opposite, and soon after six the numbers had generally increased. People came from all directions for miles around, some even long distances – on foot, horseback, and in numerous vehicles, and evinced deep interest in the event. As the hour named had passed, some grew rather impatient, and it was not until about half past six that any preparations for firing was obvious; but about that time, Mr Phillips, of Westbury Brook Mine, was observed in the quarry, talking with the men for a few minutes, and then passed on up to the hill, by the engine-house, and across the tips, and in a few minutes the red flag, or danger signal, was put on the top of the rock. The people were motioned away from the rock, and the quarry fuses were lighted, and the men scampered away for protection. All was now intense excitement and expectation, but some fifteen to twenty minutes elapsed before the explosion occurred. After the expiration of nearly twenty minutes (seventeen I counted) the charge was discharged – not making much of a report, but effectively lifting the whole mass of rock (from side to side of the knoll) several feet, for a few moments, and then sunk down, but thoroughly broken to pieces. If Mr Symonds did not include in his programme, the toppling over of the mass of rock, he may be congratulated on having attained entire success. He had a number of oak poles threaded through with chains placed on top of the rock, in line with the subterranean passage to the chamber containing the charge of powder, and these, when the explosion lifted up the rock, looked like a piece of net-work, from the place I occupied. As soon as the discharged was effected its work a hearty shout of hurrah was raised, this was not continued, as most of the people left the hill to hasten to the quarry. I was amongst some of the first arrivals, but instead of going down the road, in front of the quarry, I followed a few others up the bank, or outer lip of the quarry, thus getting a full view by looking down into it. As soon as we could scramble up the steep (sic) and look over, we saw men fallen and falling in the midst of the dense fire-damp, or fumes of gunpowder smoke. They fell like men shot. On coming into contact with the dense fumes there was first a jerk, or jump of the body, then a contortion or twist of it, and immediately dropped. The whole was almost the work of a moment. It was a distressing scene, but noble and heroic were those at hand, as men readily ventured their own lives to try and rescue the fallen; and two of the deceased are said to have perished in the attempt to save others. Eight are said to have fallen under the destroying fumes, but four of them were resuscitated by the kind and persevering efforts of the volunteers, who took them in hand, and everything possible under the circumstances which could be done for the others was done; indeed it was not till more than half past eight that the remedies were discontinued. They consisted for the most part in the application of cold water, artificial respiration, and thrusting the head into a hole in the earth, or heaping turf over it. . But all these remedies in the case of the four referred to were without avail; in the fact there is reason to believe that there was no chance with them from the first, as it is believed that they were dead already. The weeping of women, and the shrieks of relatives, as the real fact became known, and the dead were recognised, was truly distressing to hear. The names of the four deceased men are Thomas Goode, of Mitcheldean; Hiram Baylis and John Griffiths, both of the Plump; and William Tomlin, of the Meend, Cinderford. I understand that most, if not all, were married men, and leave families. It may be out of place to notice a report in circulation, namely that the firing of cannon so distinctly heard during the efforts for resuscitating the unfortunate victims of the Plump Hill was done for the raising of the dead body of the young man drowned in the Severn, near Newnham, on the afternoon of the same day. The firing was in rapid succession, and continued for some time. The body was afterwards recovered.

For information, I have a copy of the CD titled:
Gloucestershire Monumental Inscriptions 2003
Index of Memorial Inscriptions for Gloucestershire 2001
Catalogue of memorial and Burial sites for Gloucestershire 2002
Fosbrook's Bigland Memorials of Gloucester City
Reference 711.

It looks like this is the following item: https://gfhs.org.uk/products-page/cddvd/m-i-s/monumental-inscription-2003-2/

It includes M.Is for Drybrook, but does NOT include the MI for Hiram Baylis.

ABird