What is the difference between a CAS and ST Ward/Postcode sector and why?
In order to maintain confidentiality for the Standard Tables dataset (which contains the most information at the finest level), a higher threshold on the number of people and households was required. This means that some wards and postcode sectors fell beneath this threshold, in this case they were merged with neighbouring wards or postcode sectors. A full explanation is available on the National Statistics Geography web site.