In recent years, the property postcode has been logged as part of the sampling process and this gives location information. While non-domestic properties have unique postcodes domestic properties are assigned to a small number of properties in the same location. Generally, it is expected that properties with the same postcode will be of similar age since they usually refer to a single street or part of a street. Using a corporate database, the most likely property age band was determined for each post code. In order to assess the level of accuracy of this assignment a simple table was constructed showing how the assigned property age compares to the assigned age through the postcode. As can be seen from Table this introduces only a small number of errors. Utilising the property age band, the variation with property age could be determined (Figure ). For a variety of reasons (e.g. incorrect postcodes) property age bands could not be assigned to 725 properties and these were assigned to "other" group. This group constitutes less than 2% of the properties sampled so can be safely ignored. Surprisingly, lead non-compliance is not highest in the oldest properties but for those built between 1920 and 1944. It is noticeable that lead compliance is not zero for properties built after 1974, when the installation of lead service pipes was banned. Investigations into some of these infringements found that a substantial number were examples of older properties embedded amongst new properties and hence the infringement frequency amongst unleaded properties is even smaller than that estimated.