Grid References and Ordnance Survey Maps

In addition to the verbal description of the meeting place for a walk, there is both a map number and an Ordnance Survey grid reference.
There are two types of maps used, for example: L167 and E183. L refers to the pink covered Landranger Series, scale 1:50000. E refers to the orange covered New Explorer Series, Scale 1:25000 The explorer's scale consequently shows more detail and has better resolution.
The maps which cover most of the West Essex Ramblers' Walks are:
E174 - Epping Forest and Lee Valley E175 - Southend-0n-Sea and Basildon E183 - Chelmsford and the Rodings E195 - Braintree and Saffron Walden	L166 - Luton and Hertford L167 - Chelmsford and Harlow L177 - East London
There are three ways of generating a Grid Reference (GR): 1. A 6 figure GR when quoting the map to use; 2. A 12 figure GR referred to the UK map origin; 3. A 2 letter plus 6 figure GR also referred to the UK origin. SCROLL DOWN for more detail.	. eg: 455991, map L167 or E174 eg: 545500,199100 eg: TQ455991

Three ways of generating an OS Reference point
1	A six figure Grid Reference This is the popular method, but you must quote the relevant OS Map number. The first 3 figures are distances to the right on the map (known as Eastings), the second 3 are upwards (Northings). The first 2 figures give the number of the square which is shown on the map at the top, bottom and sometimes in the middle of the map. The 3rd is an estimation in tenths of the square (to the right, east) along the square. Similarly the last 3 figures apply to the squares (going upwards, North) to the squares on the side of the map. Example: Theydon Bois Station GR 455 991, L167 or E174. As behind the West Essex Logo at the top of Page	Illustration of obtaining / Reading 6 digit GR Click here for a larger diagram 6 digits in pdf
2	A twelve figure Grid Reference This method is similar to method 1 but results in a distance in metres from the UK origin. The map shows in the top left hand corner an extra digit (hundreds of kilometres) to add to method 1's first 3 digits and you need two noughts at the right end to make it metres. If you move east and get to an 00 (ie another 100km) add 1 to that extra digit! The next 6 digits are similarly formed when moving upwards (North) The number can be used in www.Streetmap.co.uk by, for example, entering 545500,199100 (no space after the comma) and selecting the box OS gets a street map of Theydon Bois with an arrow pointing to the station. Zoom out to the 3rd size to get the OS map (at 1:25000) which is printable.	Illustration of 12 digit GR & TL/TQ GR Click here for a larger diagram 12 digit TL TQ in pdf
3	A two letter plus six figure Grid Reference This method uses a 2 letter code which represents 100km squares East or North from the UK origin, plus the 6 figure GR of method 1. Every map may use 1, 2 (or possibly 4) different "2 letter" codes: it depends whether the map's grid goes from 99 to 01 in the Eastings or Northings. Landranger (1:50000) maps have a water mark on them of the appropriate letters and the letters change every time you pass the 00 square. Explorer (1:25000) maps show information in the Legend under "THE NATIONAL GRID REFERENCE SYSTEM". Use method 1 to determine the 6 figures. The number can be used in www.multimap.com by, for example, entering TQ455991 in the "GB postcode or place" gets a street map of Theydon Bois with the station circled. Zoom out to the 3rd size to get the OS map (at 1:25000) which is printable.