The Cathie Marsh Centre for Census and Survey Research
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UK area look-up tables

Use look-up tables (the updated version within Geoconvert online system, including 2001 Census areas)

The original look-up tables produced by this project before the 2001 Census were discontinued in 2008. The main feature in them that is not included in updated versions is the imputation of postcodes that are incomplete or invalid, by replacing them with a nearby valid postcode)

View project documents


ESRC’s Census Development programme 1999-2001.
Award holder: Ludi Simpson.
Researcher: An Yu

The central aim of this project was to establish readily available database look-up tables, which will allow conversion between UK census, postcode and administrative geography:

These look-up tables were made available through web-based front-end matching software and documentation.

Routines have been stored for later use with databases referring to future and past years.

The All-Fields Postcode Directory (AFPD)

This directory is key to the research. On one record for each postcode in the UK the following ‘geographies’ are recorded:

Postal geographies

A hierarchy of postal areas containing postcode districts containing postal sectors containing postcode units.

1991 Census geographies

A hierarchy of county-level areas containing districts containing ward-level areas containing ED-level areas.

Administrative geographies, each as at 1st April 1998

In general these are not hierarchical:

The quality of the AFPD is being studied as part of the project: (i) its internal quality and consistency, and (ii) the consistency of the look-up tables it provides when compared with an alternative approach based on Addresspoint, digitised boundaries, and GIS software.

In future years, the look-up table will be updated, including with the 2001 Census. The routines will be designed so that they can be used with look-up files other than the AFPD.

The project is part of ESRC’s Census Development programme 1999-2001. Director: Ludi Simpson. Research Staff: An Yu; collaborators: Mike Noble (Oxford University) and David Avenall (East Dorset Council).

The AFPD, version 1999/1, has been bought by ESRC from the Office for National Statistics for academic research purposes. In its raw form it is available from MIMAS.


Project documents

Publications:      Ludi Simpson (2002) Geography conversion tables: a framework for conversion of data between geographical units. International Journal of Population Geography, 8 (1): 69-82       Ludi Simpson and An Yu (2003) Public access to conversion of data between geographies, with multiple look up tables derived from a postal directory. Computers, Environment and Urban Systems, 27: 283-307.

Download summary of completed project (June 2001)
Word format or Adobe PDF format

Download final report of completed project (June 2001)
Word format or Adobe PDF format

Download project proposal

Describes the project aims and methods as proposed and approved (with restriction to look-up table based on the 1999 AFPD)

Download November 2000 Report and documentation of website

Describes progress, and specifies the method of constructing lookup tables and data conversion used in the website as at November 1st 2000. The site and its documentation will be updated in the coming months, before the end of the project in March 2001, when it is expected to transfer to MIMAS.

Download May 2000 report on the All Fields Postcode Directory

Quantifies the quality and completeness of the ONS All Fields Postcode Directory (AFPD) for 1999 (version B). It concludes that the file is sufficiently complete to use for look-up tables on a trial basis. It makes recommendations for (a) improved internal consistency, (b) integration with related government initiatives including the 2001 Census, and (c) historical information.

University of Manchester CCSR