There was a lot of ill informed and under researched commentary by the type of pseudo-expert listened too by Nimby groups (such as Ian Mulheirn) about the discrepancy between the headline population levels and the previous mid year population estimates, claiming the population estimates were exaggerated and hence we were planning for a ‘ghost population’. Ill leave the household formation issue separate as there is widespread agreement now that household formation and number of households build are spatially autocorrelatated (indeed ministers have quoted me occasion on this).
The big mistake is not understanding that they are not comparing like for like. The mid year population estimates include an allowance for underenumeration (that is undercounting people that exist), funding and the standard method depend on the mid year population estimates NOT the raw first census results. Some of the issues were unique to the 2021 census such as holding the census in the midst of a pandemic when many short term contract workers and students were away; but much of this is systemic especially in London where there are larger numbers of inherently difficult to count households such as from ethnic minorities. Newham for example claimed from its own data on GP rolls and school rolls that the 2011 census undercounted its population by as much as 20,000. Many Boroughs are making similar claims now.
So as the preliminary results from the 2021 census undergo similar checking and adjustment they will rise. There will of course be LPA by LPA adjustments. What is striking is despite the absence of students they showed far larger populations than expected. 145,000 rather than 129,000 as expected. Similar for Oxford. When you add back the missing students it will rise still further. So Cambridge will have to plan for 12-15% higher housing numbers than they predicted (Cambridge as opposed to South Cambridge element) in their recent local plan. Another new settlement’s worth maybe?
Perhaps some of the census/housing numbers experts from the major consultancies can suggest at what point the revisions will make way into mid year and household estimates.
Note: I now know mid-year population estimates will be rebased to underenumeration corrected 2021 census data in Spring 2023.