Ordnance Survey maps of County Durham annotated by the Sunderland Valuation Office for the purposes of the Finance Act 1910.

The printed base maps used by the Valuation Office were produced by the Ordnance Survey at various dates between about 1840 and 1920, with the majority dating from between the late 1880s and about 1914. In a few cases the original maps were replaced by copies made after 1920, probably because the originals had become damaged or badly worn through use. In some other cases, the date of printing or revision can no longer be read due to the edges of the sheet having perished or worn away. The coloured MS additions showing property boundaries and hereditament (i.e. assessment) numbers were added by the district Valuation Offices between 1910 and about 1920, and some sheets also bear later annotations; for the majority of the MS additions no date is shown. Since it is impossible to date most individual sheets with any precision, the catalogue entries have adopted the date format of c1910.

Where a map is described as having two or more parts, each now needs to be ordered separately, e.g. instead of ordering IR 129/6/18, order IR 129/6/18 part 1 or IR 129/6/18 part 2.