Clive Betts (Sheffield, Attercliffe, Labour)

To ask the Chancellor of the Exchequer if he will list for each parliamentary constituency the ratio of those aged 18 years and over at the last census to the number of registered electors, in order of the size of the ratio.

John Healey (Financial Secretary, HM Treasury; Wentworth, Labour)

holding answer 12 July 2005

The information requested falls within the responsibility of the National Statistician who has been asked to reply.

Letter from Jil Matheson to Mr. Clive Betts, dated 14 July 2005

The National Statistician has been asked to reply to your recent parliamentary question concerning the ratio of the population, aged 18 and over, recorded in the 2001 census to the number of residents who were registered to vote in each parliamentary constituency. I am replying in his absence. (10815)

I am placing in the House of Commons Library, a table supplying the requested information.

In order to give an estimate of the number of electors on census day (29 April 2001), a weighted average is taken of the 1 February 2001 and 1 December 2001 electoral data. Data are given for parliamentary electorates. Data for the local/European electorate, by parliamentary constituency are not readily available for 2001

It should be noted that the ratio of residents who are registered to vote in each constituency is not a reliable estimate of the registration rate of the eligible population: the resident population aged 18 and over is not the same as the number of people eligible to vote.

The UK parliamentary electorate excludes residents of countries other than the UK and the Commonwealth and includes UK citizens resident abroad. In addition not everyone who is usually resident is entitled to vote (foreign citizens from outside of the EU and Commonwealth, prisoners, etc. are not eligible) and people who have more than one address may register in more than one place. Also there is inevitably some double counting of the registered electorate as electoral registration officers vary in how quickly they remove people from the registers after they have moved away from an area or after they have died. This latter is the main reason why in some constituencies the population aged 18 and over is less than those registered to vote. These factors may have a different impact from place to place.

Furthermore, you should note that the Office for National Statistics (ONS) has revised the mid-2001 population estimates since the publication of the 2001 census results. In September 2003, revisions were made that added approximately 193,000 to the population of England and Wales. This revision primarily related to the addition of a number of young males that were not captured by the census. In September 2004, ONS made further revisions as a result of concluding studies designed to improve population estimates in the areas that proved hardest to count in the 2001 census in England and Wales. The results of this work showed that the one number census (ONC) worked well in most areas, but that there were a few cases where it was not able sufficiently to adjust for exceptional circumstances. The analysis showed that there was a need for revisions to the 2001 census based population figures of around 107,000 for England and Wales as a whole. The adjustments were included in the new mid-year population estimates for 2001, published in 2004. The census database itself was not revised following the publication of these adjustments. More details on these issues can be found at: www.statistics.gov.uk/lastudies .

Any comparison of these data with figures for other years should be made carefully as electoral legislation and other changes (such as EU expansion) can change the size of the electorate.