The original role of the waterway was to ship coal from the field at Newent. Work started at the Gloucester end in 1790, and by 1798 the canal had advanced as far as Ledbury. Money then ran out, however, and for more than 40 years the project remained unfinished.
Only in 1839 did work start again, and Hereford at last came on stream in 1845. For a few years the canal earned reasonable income, with barges carrying timber, corn and cider among other products; but its staple, the Newent coal, proved disappointing - of poor quality, and hard to get - and in 1881 the waterway was officially abandoned.
Ideas about restoration began to flicker with the formation of the Herefordshire and Gloucestershire Canal Society in 1983. The first schemes were modest - to reopen one or two short stretches, and repair a few structures - but plans grew more ambitious, not least when the society was converted into a charitable trust in 1992; and now, according to Nigel Bailey, its secretary, "the long-term aim is nothing less than to restore the entire canal."
At the moment work is concentrated at Over, just off Gloucester, where the canal used to lead off the Severn. In the 1890s, an isolation hospital went up there on a shoulder of rising ground, and the builders dumped vast quantities of earth, ash and rubbish into the old basin where barges used to moor before going through the lock to the river.
In time, the march of progress overtook the hospital as well; it closed six years ago, and its former grounds now belong to the developer Swan Hill Homes, which is about to build 30 "executive-style" houses on the land.
But, by patient wheeling and dealing, the H&G Trust has secured for itself the site of the lock, the basin and the first hundred yards of the canal proper. It also won the right to carry off unlimited supplies of dark- red bricks from the old hospital buildings that are being taken down. The canal-men's trump card is that by recreating an attractive wharf and basin, they will greatly enhance the value of the new houses that immediately overlook the water.
At the moment, the site is a terrific mess. Demolition work was temporarily suspended when one of the outlying wards was found to contain three species of bat - which are legally protected. Nevertheless, huge heaps of ground- up brick rise like pyramids among the ruins.
At river level, Trust volunteers have dug out the old canal basin, down to a base of glutinous grey mud. They have built most of a new wharf wall, of reinforced concrete below and brickwork above, have started work on a slipway, and have cleared trees and scrub from the flood plain beside the Severn.
Normally, half a dozen local enthusiasts plug doggedly away at weekends; but earlier this month they received a tremendous boost when 130-odd members of the Waterway Recovery Group - the national co-ordinating body for voluntary labour on inland waterways - arrived in force to hold their annual reunion weekend on the site. Having worked at other camps during the summer, the men and women are each paid pounds 8 a day and travelling expenses for the privilege of toiling like slaves, getting plastered with mud, and sleeping on the floor of the gym or assembly hall of a nearby school.
On the day I visited, a line of amateur bricklayers was making a most professional job of the basin wall. Another gang was laying a new surface on a section of towpath. One man was driving a heavy digger, another a dump-truck.
Huge bonfires were burning rubbish from the flood plain and, up in the ruins of the hospital, yet another little team was chipping the old black mortar off salvaged bricks.
Mike Palmer, burly national chairman of the WRG, turned out on a raw November day in hard hat, red T-shirt and shorts, with a black bin-liner split at the end and pulled down over his torso like a tabard. "Canal restoration used to be all tree-bashing or shovelling mud by hand," he explained. "Now the work we're being asked to do is more and more specialised. We're using machines all the time, and for that reason we do a great deal of training on the job."
Partly because most of the materials are free, but mainly because the work is being done by volunteers, the project at Over, which would have cost at least pounds 250,000 if carried out by contractors, should be completed for less than a tenth of that amount. This, of course, is only a small part of the restoration; but the H&G Trust has already won a major victory in securing the support of local authorities, who believe that if the canal can be reopened it will prove a strong tourist attraction and bring much holiday business into the areas. The result is that if anyone now tries to put up a building along the line of the waterway, the application will be vetoed.
Restoration projects of this kind have recently become fashionable. "Canals are starting to get major funding," said Mike Palmer, "but only because volunteers have been hacking away at little showpiece schemes for the past 35 years. Here at Over, if H&G hadn't gone for it - if it hadn't been for us idiots wading around in the clay - the site would have been covered with houses, and the canal would have disappeared for ever."
Further information from Nigel Bailey on: 01452 533835 or website: http://www.h- g-canal.org.uk