IT came very close to "shock and awe". The huge landslip on the Cleveland Hills in June 1872 aroused what a newspaper described as "intense wonder not unmingled with awe". About 200yds of the Cleveland escarpment at Hasty Bank, south of Stokesley, broke away, sending gigantic rocks and many tons of earth crashing down the hillside.

Heard up to several miles away, the noise of "the falling masses" sounded, said the newspaper reporter, like "the distant boom of cannon mingled with the sharp report of a cracking rifle".

The great slip left behind a craggy precipice some 80ft high, whose still-sheer edge today carries the Cleveland Way and the Coast-to-Coast walk. Down below, a particular "wonder" of the fall was a five-yard section of stone wall, standing intact despite having been carried 18yds downhill.

Covering 20 acres with debris, the fall was believed to have been caused by the waterlogging of a hillside by protracted wet weather, which climaxed with a thunderstorm on the night of the fall. Old jet mines whose roof supports had become rotten probably also contributed to the collapse, the scale of which almost persuaded one nearby resident that "t'hills was fallin' down".

But, dramatic though it was, this enormous landslip would probably have slipped quietly into history but for a peculiar set of circumstances.

The first was that the fall buried about 260yds of the road into Bilsdale from Stokesley and Great Broughton - now the B1257. Another was that this section of the road lay in the parish of Ingleby Greenhow. A third was that the local road pattern removed any need for Ingleby Greenhow people to use that particular length of road, which they still rarely travel today. But at that time - the crucial final circumstance - parishes were financially responsible for the upkeep of the highways.

Naturally, the folk of Bilsdale and Great Broughton wanted their road back. Equally naturally, the folk of Ingleby Greenhow didn't see why they should pay - not least since there was an alternative road, albeit two miles longer and with numerous gates.

The result was an astonishing battle which, as a new booklet devoted to it says, has entered local folklore. Numerous inspections of the blocked road were made. The district's highways board, with overall responsibility for roads, met several times at the road.

Core samples of the debris, and measurements of its movement over time, were taken. Summonses and writs darkened the moorland air. Barristers' opinions winged back and forth. The conflict ran for almost four years, with the most determined travellers meanwhile picking their way along the debris, resolved not to lose their road.

What prolonged the dispute were some intriguing legal arguments. But the scene was set shortly after the slip when the highways board agreed with Ingleby Greenhow that the road should be abandoned and improvements made to the alternative route, which twists through farms at the foot of hills, before climbing to join the main road at Clay Bank Top, above the landslip area.

But in August 1873, 14 months after the landslip, the patience of Bilsdale farmer John Johnson snapped. He obtained a summons against the highways board, demanding that it order the reinstatement of the road. His solicitor wrote: "It is no answer to say that the bank which has fallen is not solid and substantial enough. It is quite sufficient to support any weight of carriage ... The public have a right to their road and to call on the Greenhow Township to make it."

Johnson's lawyer described the road as "ruinous, miry, deep broken and in great decay". Only too happy to agree, Ingleby Greenhow and the board went further, insisting that the road was totally destroyed. This allowed them to argue that their duty to "repair" the road no longer applied. The precedent of a road at Hornsea that fell into the sea suggested that a parish's liability did not extend to constructing a new highway to replace one that had disappeared.

But legally closing the road posed a problem. This could be done only if two magistrates certified the route to be "unnecessary".

No doubt aware that Lord De L'Isle, Ingleby Greenhow's lord of the manor, favoured closing the road, Stokesley magistrates dismissed Johnson's demand.

But Bilsdale pressed the matter to York Assizes, where another aspect loomed large. Had the road simply been smothered and shifted by the debris, or had it been lifted from below? Crucial to whether or not the road was "destroyed", this was why borings were taken. Seemingly helpful to the Greenhow cause, these discovered only loose soil and water where the foundations should have been.

Greenhow also produced evidence that the land was still slipping. It pointed out that Bilsdale folk had independently planned an improvement to the contested road, which they would have paid for themselves had they been able to obtain the land.

Greenhow added that a planned railway for Bilsdale, never built, would "take most of the traffic of the district". But above all it emphasised that the parish had spent £180 widening the alternative route, which Lord De L'Isle had fenced at his own expense. Evidently a little put out at the lack of instant gratitude, it protested: "The prosecuting township cannot say that we have not attempted to accommodate them."

On July 17, 1874, an assizes jury made the 80-mile round trip to see the disputed road for itself. The immediate upshot isn't clear, but on March 19, 1875, with the case switched to the civil list, an assizes judge ruled in Bilsdale's favour - with the unusual proviso that his judgement be subject to an assessment of the road by an independent engineer.

Confirming the original view of Johnson's Stokesley solicitor, this expert, Richard Cail, of Newcastle, reported in November that it was "practicable to form a permanent and passable road along the old track". He estimated the cost at £341, a little less than the £100,000 suggested in court for Ingleby Greenhow.

So the old road was re-made - happily with the help of Bilsdale farmers, who contributed transport and labour, but not cash - what would you expect? Predictions that the land would slip again proved groundless. Nevertheless, in 1930 North Riding County Council constructed a better road alongside the original. But the old route remains a right of way - a little-used footpath within the edge of a conifer plantation that now clothes most of the landslip area.

Brian Marsay, author of the new book, allows the story to unfold very largely through the original legal documents, which he augments with illuminating brief accounts of the history of roads in England and the duties of a parish highways surveyor.

His home, Rose Cottage, is tucked at the foot of the contentious landslip. As he sits in his garden, hearing "the Honda and Yamaha superbikes" screaming through their gears as they zip up Clay Bank on their way to Helmsley, he thinks "how different things could have been had the Greenhow residents won the case."

The circuitous route they had hoped to foist on future travellers would have presented an obstacle almost as effective as a landslip on the notorious Bilsdale TT.

* 'T'ills Was Fallin' Down": The Great Landslip of 1872 by Brian Marsay (Bilsdale Study Group, £6.50) is available from bookshops in Stokesley and Guisborough and the village shop in Great Broughton)