qgis - Convert UK OS grid coordinates to decimal degree WGS84?

I've got a list of coordinates in the UK Ordnance Survey grid system e.g. "NZ 27 41" or "NZ 284 449". How do I convert them in QGIS 2.10 to decimal degrees so I can map them in QGIS in WGS84? BTW, is there a way to deal with the spaces in those coordinates?

Answer

These are OS grid references, to convert them OS coordinates you can use 'ng converter' which is free from here:

http://digimap.edina.ac.uk/webhelp/os/data_information/os_data_issues/ng_converter.htm

Before using 'ng converter' you will first need to do a find and replace operation on the list of grid references to remove the spaces (easy enough in, say, a spreadsheet).

Load the output of the converter into QGIS as a delimited text file with the CRS EPSG:27700. From here the data may be 'saved as' an EPSG:4326 (WGS84 lon/lat) shapefile (or used as it is, converted to EPSG:4326 on-the-fly).