William's men set out to establish, for each manor, who owned it before 1066 (always referred to as 'in the time of King Edward' as William would not acknowledge Harold's claim to the throne), who owned it at the time of the survey in 1086, what its value was in 1066 and 1086, as well as the working population, and the natural resources like pasture and woodland.

The Domesday entries for Ilkley contain several terms no longer in common use. The manor was the central unit of landholding in Domesday, and through it administration and taxation were carried out. Taxation was on the basis of the number of carucates of land held. The carucate, like the rateable value of the 20th century, appears at the time of Domesday to be purely a value for taxation and its relationship to actual acreage on the ground appears to vary significantly, but the carucate is often said to contain 120 acres. The league is generally believed to have contained twelve furlongs, or one and a half miles, but again this is more a guide to order of magnitude rather than an exact measurement. In addition, the entry for Otley, which lists neat squares of underwood, woodland pasture, and arable land makes it clear that dimensions are only intended to give an indication of the total area rather than any particular shape.

The Domesday book is arranged by county, and then by landowner. In the list of the Yorkshire lands of William de Percy, we find two entries pertaining to the parish of Ilkley:

Manor. In Illicleia (Ilkley) Gamall had 3 carucates of land taxable where 2 ploughs are possible. Now William has it. Waste. Value in the time of King Edward, 20 shillings. A church and a priest there. Woodland pasture 1 league long and 4 furlongs wide. The whole manor, 1 league long and 8 furlongs wide.

Manor. In Nacefeld (Nesfield) Gamalbarn had 3 carucates of land taxable, where 2 ploughs are possible.

William de Percy held about eighty manors in Yorkshire and thirty in Lincolnshire, as well as further lands in Essex and Hampshire in 1086. He is reputed to have come over to England from France in 1067, and was associated with the refounding of Whitby Abbey. William de Percy died in Palestine on the first crusade.

Of the previous English landowners, Gamall and Gamalbarn (i.e. son of Gamall), we know nothing with certainty. Within the lands granted to William de Percy in the West Riding a number are described as belonging to Gamalbarn and it is probable that he had held lands in Beamsley, Askwith and Addingham.

The list of possessions of the Archbishop of York mentions further places in the parish of Ilkley. His manor of Otley included several outlying farmsteads or berewicks. Stube (Stubham), Middeltune (Middleton), and Ilecliue (Ilkley) are included in the list of these, but individual details of these holdings are not given.

So we know that in 1066 Ilkley included at least five centres of population. It seems likely that the manor of Ilkley was centred close to the Parish Church, and the manor of Nesfield close to the existing village. The berewick of Middleton was probably sited near the old village of Middleton, at the triangle of old lanes above Curly Hill, and the berewick of Stubham was probably sited at Low Hall, on Rupert Road. The location of the Archbishop's berewick in Ilkley is uncertain, but possible locations include Holling Hall, Ben Rhydding near the Wheatley Hotel, and Todthorpe, close to the existing house of this name on Hangingstone Road.

But by 1086 and the Domesday survey, these communities had been all but wiped out. The English population of the parish had been, at best, transported to their new Norman landlord's other manors. At worst they had been put to the sword like large numbers of others and their houses burnt and crops destroyed.

Ilkley was entirely waste, and the Archbishop's manor of Otley mainly waste, its value being less than a third of what it had been before the conquest. The scant details provided for Nesfield lead one to suppose that this holding too was waste. In the West Riding as a whole, many places are described as waste or partly waste, and many more are without details implying that they too were waste. Almost all the land higher up in Wharfedale comes into this category and it is clear that upper Wharfedale was almost completely uninhabited.

The waste was largely as a result of the Conqueror's 'harrying of the North' in the winter of 1069-70 seventeen years before. The ancient kingdom of Northumbria was the centre of unrest against William's occupation and York changed hands repeatedly during continued fighting between the Normans and the English in alliance with the Danes. When William finally retook York, he set out to ensure that the North could no longer form a base for rebellion against him and embarked upon a campaign of destruction against Yorkshire in particular, but extending also into Cheshire, Shropshire, Staffordshire and Derbyshire and the immense destruction caused is apparent in the Domesday record.

It is not clear, however, whether the villages described as waste in 1086 were actually laid waste by William's men. It is possible that migration took place from untouched villages in the marginal land of the Pennines to those with better land to the East whose populations had been wiped out during William's campaigns. So we cannot say with certainty whether William's men carried their ruthless devastation into Ilkley itself or whether the village had lain deserted after William de Percy transferred the population to another of his manors. Whatever the cause of Ilkley being described as waste, we may be sure that the priest at the church had scant congregations compared to his pre-conquest predecessors who had seen the erection of the splendid crosses, still standing in the Parish Church, many years before.