National grid to lat long conversion

[Astley.lejasper at gmail.com]

Hi,

I have a load of British National Grid references that I want to
convert to decimal degrees so I can create a google KML file. Does
anyone know of a module to do this?

I've looked at http://pygps.org/#LatLongUTMconversion but am not
really up to speed with projections and all this other mapping stuff.

I want to take something like

x = 417512 y = 315098 (SK 17570 15100)

and convert it to a google compatible decimal degrees

lat: 52.733255N Long: -1.741239

Any help would be great