Postcodes on envelopes
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Making its mark: Forty years of the postcode

7 April 2014 Last updated at 08:07 BST

The postcode was rolled out nationally 40 years ago in Norwich, speeding up the sorting of mail.

Since then it has proved essential for finding directions with sat-nav systems.

It is also used for calculating insurance premiums - not without controversy.

Laura Trant reports.