OSGB Excel routines by Phil Brady
These spreadsheet routines can import GPX files into a spreadsheet for convenient examination and manipulation, can drastically compact the size of the GPX routes and tracks with minimal loss of resolution and can export data in both GPX and KML format for use with Google Earth.
Additionally, there is a comprehensive set of routines for converting Ordnance Survey references (including WGS84 latitude/longitude), computing distances and bearings, computing grid and magnetic variations and for locating GB postcodes and US zip codes.
They are free for non commercial use and private study at
Author: Phil Newby