A Quick Guide .....

to getting the grid reference on an Ordnance Survey map right first time. The best maps to use are the 1:50,000 Landranger series or, for more accuracy, the 1:25,000 Pathfinder series. The latter maps are the best for finding your way around, especially on foot, as footpaths, hedgerows and other features are clearly shown.

  1. Hold the map the right way up so that you can read the print. North with be at the top of the map.
  2. Now locate the position you wish to identify on the map, look for hedgerows, power lines and buildings which will help you fix your position. In more remote areas you may need to look at the contour lines to identify features like valleys with streams, rocky outcrops and the peaks of hills.
  3. Having identified your position on the map look for the blue vertical lines running from top to bottom of the map. You will note that they are numbered consecutively across the top and bottom of the map from left (west) to right (east). Your position will be between two of these lines, divide the space between the lines into 10 and judge how far along the your position is from the left hand line. For example, if the left line is numbered 41 and your position is 5/10ths of the way across, then the first three numbers of the reference will be 415.
  4. Now look at the lines that run horizontally across the map from left to right, these are numbered from the bottom (south) to the top (north) on both right and left hand sides of the map. As before, your position will be between two lines, divide the space into 10 and judge how far your position is from the lower line. For example if the lower line is numbered 94 and your position is 4/10ths of the way up from the line, then the second three numbers of the reference will be 944.
  5. The full reference will be 415944.
  6. All you need to do now is add the reference letters appropriate for your map, in Shropshire they will be either SJ or SO. If you look on the right hand side of the map where the key to symbols is displayed it will tell you which letters to use.  
  7. The final reference number will therefore be SO415944.
  8. If you have the OS 1:50,000 map for Ludlow and Wenlock Edge (Landranger 137) and look this reference up you will find that you are on the top of the Long Mynd at the trig point at Pole Bank.
  9. It is easy when you know how and have had a bit of practice. Although we prefer that records contain a grid reference do not worry if you cannot work it out but please try to describe where you are as accurately as possible - you may just have seen a rare bird and you may need someone to confirm your sighting.

A useful website that will help you locate grid references can be found at http://wheresthepath.googlepages.com/wheresthepath.htm This site provides an aerial view and a map side by side. Hover the cursor over either the map or the photo and the exact grid reference will appear in a display box - it has to be manually copied so take care with transcription. However, it can be very accurate and you may see the actual tree that the bird was sitting in! Bear in mind that the photographs may be some years old and what you see on the ground may differ if there has been development or cultivation e.g.a stubble field on the map may now contain another crop or a wood may have been felled, or planted!

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