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A shift in the compass

When you’re out and about teaching the kids orienteering or simply going for a countryside ramble, it’s worth bearing in mind that your compass doesn't always point exactly grid north.

Geomagnetic North Shift

Magnetic north had been a few degrees west of grid north in the UK since the 1600s. Then, in 2014 it shifted to the east of grid north, for the first time in modern map-making history. This was a gradual change that happened over the next decade or so, starting in the South-West and gradually covering the whole of Great Britain. 

Three Norths Converge

In addition to magnetic and grid north, true north is now starting to come into alignment. True north represents the direction of longitude lines converging at the Earth's geographic North Pole—a fixed reference for navigation and mapping purposes.

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Geomagnetic Forces and Map Projections

Map projections, like the transverse Mercator projection employed in the British National Grid, reveal intriguing patterns of convergence. Longitude lines curve away from the straight grid lines, exhibiting spatial variations across the grid area. The central meridian line, located at 2°W or 400,000m E on the British National Grid, holds a significant position where our chosen longitude aligns with the vertical eastings grid line.

Temporal and Spatial Alignment

As the shifting magnetic north approaches the central meridian line, a triple alignment of magnetic north, grid north, and true north is expected to occur. 

This temporal alignment started at Langton Matravers, west of Swanage, around November 22. Progressing further, the alignment reached Poole by Christmas.

The Journey of Alignment

Continuing its trajectory, the alignment will traverse through Hebden Bridge by August 2024, marking the midpoint of Great Britain. It will subsequently leave the English coast near Berwick-Upon-Tweed in August 2025. 

The alignment resumes in Scotland around May 2026 at Drums, south of Newburgh, and culminates its journey in Fraserburgh in July 2026.

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Geomagnetic Processes

The ever-changing magnetic field is governed by the geodynamo - a phenomenon arising from interactions between the flow of molten iron-rich material in the Earth's liquid outer core and the magnetic field. Buoyancy forces, convection, and the planet's rotation generate new magnetic flux, which sustains the magnetic field.


The geomagnetic alignment of magnetic north, grid north, and true north in the UK offers a fascinating insight into the dynamic nature of Earth's magnetic field. The convergence provides valuable scientific data for geophysicists and cartographers and is a testament to the complexities inherent in our planet's magnetic processes. As we further our understanding of geomagnetism, we continue to unravel the enigmatic forces shaping our world.

Ordinance Survey has created custom-made maps to help you navigate, and the British Geological Survey website has a tool where you can calculate grid/magnetic north on your trips.


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  1. Magnetic North: Magnetic north refers to the direction in which the needle of a magnetic compass points. It is the direction in which the Earth's magnetic field lines converge and is influenced by the slow movement of molten iron in the outer core of the Earth. The magnetic north pole is not fixed and varies over time due to changes in the Earth's magnetic field. For navigation purposes, it's essential to know the magnetic declination, the angle between magnetic north and true north, to make the necessary adjustments when using a magnetic compass.

  2. Grid North: Grid north, also known as map north or grid azimuth, is the north direction indicated on a map. It is defined by the grid lines of a map's coordinate system, typically represented by horizontal and vertical lines forming a grid pattern. The grid north is used in cartography and navigation to determine the direction between two points on a map or to align the map with a compass.

  3. True North: True north is the direction towards the Earth's geographic North Pole, the northern end of the Earth's rotational axis. It is the fixed reference for navigation and is aligned with the Earth's axis of rotation. Unlike magnetic north, which changes over time, true north remains constant. Navigators often need to convert magnetic directions to true directions when using a magnetic compass or map by considering the magnetic declination for a specific location.


This article was first published in December 2014 and updated in July 2023.