Are the UKCP09 grids aligned with the Ordnance Survey British national grid?

Yes and no – it depends what is meant by aligned.

In detail

The UKCP09 grids are based on (global) latitude and longitude. This means that the grid square edges do not exactly align with (i.e. are not parallel to) the Ordnance Survey British national grid due to the curvature of the Earth.

However, the UKCP09 grids are aligned with the Ordnance Survey British national grid in so far as they sit on top of the UK when plotted on the same map (e.g. in GIS software).

Find out more

• The Ordnance Survey Guide to coordinate systems in Great Britain contains a map (Figure 8) which illustrates the difference between a global latitute/longitude coordinate system (in solid lines) and the Ordnance Survey British National Grid (in dotted lines).

• The User Interface has information on all the grids used in the projections. This includes descriptions of the grids, the centre co-ordinates of each grid cell, co-ordinates of the corner grid cells and CSV and shapefiles of the grid geometries.