Medieval kings in general were not interested in the number of people ("souls") living in their kingdom. Souls were the church's business. Kings were interested in the amount of tax they could expect, and the profits from the land that the King owned directly (those lands were scattered all over the kingdom).
William the Conqueror for example had the Domesday book compiled in order to get an overview of those things:
The Domesday book was very precise on many accounts - Wiki says it contained over 13,000 land ownership records. However it says nothing about population, either because the compilers found it too hard to obtain or because their boss (the King) was not interested in population numbers.
Population was not really a relevant number. Kings might muse and speculate about how many souls their kingdom contained, but in general did not consider this information worthy of the expense required to find out exactly.
William the Conqueror for example had the Domesday book compiled in order to get an overview of those things:
The Anglo-Saxon Chronicle said:While spending the Christmas of 1085 in Gloucester, William had deep speech with his counsellors and sent men all over England to each shire to find out what or how much each landholder had in land and livestock, and what it was worth.
http://en.wikipedia.org/wiki/Domesday_book#Purpose said:Purpose
For the object of the survey, there are three sources of information:
* The passage in the Anglo-Saxon Chronicle, which tells us why it was ordered:
After this had the king a large meeting, and very deep consultation with his council, about this land; how it was occupied, and by what sort of men. Then sent he his men over all England into each shire; commissioning them to find out 'How many hundreds of hides were in the shire, what land the king himself had, and what stock upon the land; or, what dues he ought to have by the year from the shire.' Also he commissioned them to record in writing, 'How much land his archbishops had, and his diocesan bishops, and his abbots, and his earls;' and though I may be prolix and tedious, 'What, or how much, each man had, who was an occupier of land in England, either in land or in stock, and how much money it were worth.' So very narrowly, indeed, did he commission them to trace it out, that there was not one single hide, nor a yard of land, nay, moreover (it is shameful to tell, though he thought it no shame to do it), not even an ox, nor a cow, nor a swine was there left, that was not set down in his writ. And all the recorded particulars were afterwards brought to him.
* The list of questions which the jurors were asked, as preserved in the Inquisitio Eliensis
* The contents of Domesday Book and the allied records mentioned above.
Although these can by no means be reconciled in every detail, it is now generally recognised that the primary object of the survey was to ascertain and record the fiscal rights of the king. These were mainly:
* the national land-tax (geldum), paid on a fixed assessment,
* certain miscellaneous dues, and
* the proceeds of the crown lands.
After a great political convulsion such as the Norman conquest, and the wholesale confiscation of landed estates which followed it, it was in William's interest to make sure that the rights of the crown, which he claimed to have inherited, had not suffered in the process. More especially was this the case as his Norman followers were disposed to evade the liabilities of their English predecessors. The successful trial of Odo de Bayeux at Penenden Heath less than a decade after the conquest was one example of the growing discontent at the Norman land-grab that had occurred in the years following the invasion. The survey has since been viewed in the context that William required certainty and a definitive reference point as to property holdings across the nation so that it might be used as evidence in disputes and purported authority for crown ownership.
The Domesday book was very precise on many accounts - Wiki says it contained over 13,000 land ownership records. However it says nothing about population, either because the compilers found it too hard to obtain or because their boss (the King) was not interested in population numbers.
Population was not really a relevant number. Kings might muse and speculate about how many souls their kingdom contained, but in general did not consider this information worthy of the expense required to find out exactly.