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County Series map numbering

An explanation of how our County Series maps, published between the 1840s and 1950s, were numbered. When giving reference numbers for County Series Maps and Plans, always mention the county by name.

Six-inch (1:10 560 scale) full sheets

Most First Edition six-inch maps cover an area on the ground six miles east to west and four miles north to south. They are identified by the county name and a number, for example, Essex 16. This number is sometimes shown in Roman numerals.

On the indexes, the area covered by each six-inch full sheet is defined by a heavily lined rectangle.

Rectangle with 16 at the centre

Six-inch quarter sheets

Some First Edition six-inch maps and, with some exceptions, the subsequent editions of all the six-inch maps were produced as quarter sheets, covering an area on the ground three miles east to west and two miles north to south.

Each sheet is identified by the county name and number, followed by the appropriate quadrant NW, SW, NE or SE, for example, Essex 16 NW.

Numbered 2 by 2 grid

1:2500 Scale (or twenty-five-inch) plans

There are sixteen 1:2500 Scale county series plans within each six-inch full sheet. Each 1:2500 Scale plan covers an area on the ground one and a half miles east to west and one mile north to south, and is identified by its number within the six-inch full sheet, for example, Essex 16/5.

NOTE: always mention the county by name when giving reference numbers for County Series Maps and Plans.

Numbered 4 by 4 grid

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For general enquiries, complaints, feedback or suggestions, email: customerservices@ordnancesurvey.co.uk or call us on 08456 05 05 05