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That an individual has a record on the electoral roll is the bedrock on the personal data 'industry' in the UK; it is the platform on which much is built - this is because this record has a) a relatively high degree of assurance that their is an individual at a certain address with this name and date of birth, and b) that this data can be acquired for onward use at relatively small cost (e.g. by credit bureau, marketing services providers etc).
However, at present, the individual has one of the few who don't have the capability to use their electoral roll record to prove their identity. This changes when, as is now becoming apparent in the Mydex Community Prototype, a local authority is able to make that electoral roll presence available digitally for the individual to use in their personal data store.