(It should explain the honest confusion in Brad's answer. Notice the relationship between the "false origin", the "true origin", and the SW corner of the ref. The combined graticule and grid in the map below is from A guide to coordinate systems in Great Britain, a good 43-page technical document. Northing is T + Q + 858 = 0 x 500km (T is 0 large square north of S) + 1 x 100km (Q is 1 medium squares north of its parent's origin) + 858 x 100m = 185800m.Easting is T + Q + 845 = 1 x 500km (T is 1 large square east of S) + 0 x 100km (Q is 0 medium squares east of its parent's origin) + 845 x 100m = 584500m.Population and household counts are provided at a 100 metre grid resolution for settlements with a population of greater than 1000 using. The Southampton reference of SU418122 is equivalent to 441800,112200 because the SW corner of medium square " U", is 4 squares (or 4 x 100km) east and 1 square (or 100km) north of its parent large square's SW corner.Īnother example: my home town of Leigh-on-Sea, on the North of the Thames estuary, is at TQ845858. The Combined Grid Square product provides basic 2001 Census statistics for population and household counts for a combination of 1km and 100 metre grid squares in Northern Ireland. I added two red dots for the sample locations that follow. The following index map is from Using the National Grid, a two-page consumer guide. The " V" means it is in the SW corner of its parent, " S". Thus the 6-figure reference for the origin is SV000000. The origin of the UK grid (i.e., 000000,000000), is at the very SW corner of the large square " S". X, Y, Z pattern also exists inside each large square), so each medium square has a unique two letter label - one for its parent, one for itself. Now, the labeling pattern is the same for both large and medium squares (i.e., the A, B,C. (Actually, there's yet another intermediate level of squares, 10km wide, between "medium" and "small"!) In grid square the 8347 the contour lines are packed tightly today. I call them medium squares because they too, as you know, are subdivided further into 100 x 100 topographic map, small grid squares, 1km wide. A grid square is a device of the Maidenhead Locator System. Those leading figures you ask about are the Eastings and Northings of the SW corner of the "medium" square " U" which is inside its parent large square " S".Įach large square is 500km wide, as you state.Įach large square is further subdivided into 25 "medium" squares, 100km wide.
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