The thefts have become so commonplace that between Christmas and the end of January more than 1,000 tons of coal a week disappeared from the Dulais and Neath valleys, a black Klondike which is reckoned to produce the world's finest anthracite.
Security guard Christopher Jones had been in the job only a week when he was fired at three times with a shotgun and peppered with more than 50 pellets. The 18-year-old was working as a guard at the remote Sarn Helen mine, 1,400ft above sea level, when he was shot. He managed to escape in the dark and drive for help. He spent several days in hospital having the pellets removed.
His shooting, three weeks ago, revealed the extent of coal thefts in the area. At night the mine comes to life, and lights can be seen moving about the coal heaps. Peter Lloyd, a local councillor, says thieving is rampant. "I was driving home after dark and a motorcycle came across the front of me with a man in a balaclava carrying sacks of coal," he said. "Sometimes there seem to be more people working illegally at night than legally during the day."
Security lighting, cameras and guards have been installed at some sites because of the gangs' activities.
They use vans, lorries and motorcycles to take away their hauls, and long-range lookouts with radios to help their vehicles avoid patrols.
Small-scale thieves are also at work after dark. Some have been seen using mopeds and pushbikes equipped with saddle-sacks or with wheelie- bins tied to the backs to take away the loot.
In the past a blind eye has often been turned to the odd carrier bag of coal collected from the edges of the mines. But the fear in the community now is that the shooting of Mr Jones and the greed of the gangs will stop that.
Few locals will talk about the thefts, particularly since the shooting. But one man said: "For years people have taken bits of coal for their own use, but these men have gone over the edge. They are turning it into a business earning a couple of hundred pounds for a night's work. They used to go in with bags, now they go with big lorries.
"When you get that sort of money involved, you get violence. The boy was shot because of the job he was doing."
Up to 15 detectives are involved in investigating the shooting. Det Supt Wyn Phillips said: "What has come to light is that there is a serious problem of thefts of coal in that area. It is more than people taking a bit of coal for personal use."
Celtic Energy, which operates some of the biggest open-cast mines in South Wales, several of which have been robbed, declined to comment, as did other owners and operators.
The raids have revived memories of the mid-Eighties when a coal-carrying train in the nearby Cynon Valley was halted by an obstacle on the line. By the time it got going again, several hundred tons of coal had been stolen from its wagons and coal sales in the area slumped for several months. It was claimed at the time that the coal had been given away to the elderly and needy.
A worry for some locals in the Dulais and Neath valleys is that the activities of the gangs will put the spotlight on what has become almost a traditional perk.
Those who take small amounts of coal for their own use have considerable sympathy in a community which once boasted 13 pits and jobs for everyone. Since the rapid decline of the pits, life is hard and unemployment in the South Wales valleys now ranges up to 37 per cent with high rates of deprivation and low pay for those who do have jobs.
Coal stealing is not confined to South Wales, although the region's premium-value anthracite makes it the favourite target. Unemployment and household incomes that are below poverty level are the driving forces behind many of those who pick their own coal from tips and sites across Yorkshire and the Midlands.