qgis - Derive WGS84 Longitude & Latitude from British Northings & Eastings

I'm looking for a fairly simple way to append columns with WGS84 longitude and latitude to a table containing northings and eastings. The source data is Ordnance Survey's CodePoint Open, which I is I think OSBGB36. I want to use this with OpenStreetMap. I have the CodePoint data in a csv file and loaded into an MS Access database, from which I can load it into QGIS. From there I've tried exporting it with a transform operation into various file formats but this doesn't seem to do the trick. I do have access to PostGIS and SQL Server 08R2 but little experience of using sql spatial.

Answer

Try this:

1. Load the .csv into QGIS using "Delimited Text Layer" plugin


2. Define the projection OSBGB36 in layer properties


3. In "Save layer as ..." set CRS to WGS84 (this will reproject your data) and chose an output format you like

To add columns to the attribute table containing long and lat in WGS84:

1. Use "Export/Add Geometry Columns"


2. If you need a .csv again: Chose "Comma Separated Value" format in "Save layer as ..."