Ordnance Survey provides a coordinate mapping mechanism called OSTN02 for converting between British National Grid (BNG) and WGS84 Latitude/Longitude coordinates. Esri UK provides the following free software products to integrate OSTN02 coordinate trasformation into ArcGIS and ArcPad
A free extension for ArcPad 7.x - 10 which integrates the conversion, allowing the best possible accuracy of data capture through mobile devices.
To download the OSTN02 extension for ArcPad, click the link below:
To use the OSTN02 transformation in ArcGIS, please download the transformation file in NTv2 format from the Ordnance Survey website.
The free download package below contains an Add-In for ArcGIS 10 and a document explaining how to use the Add-in with the OSTN02 transformation in ArcGIS desktop software.