Hi There.
Mike Irving here, an iOS App Developer.
I have recently released a similar app, that members here may find of interest.
OS Grid Ref Compass for iPhone provides your current OS Grid Reference, OSGB36 and WGS84 data, along with your current compass bearing.
Data can be shared via Email, Tweet or Text too.
Find it in the app store here: http://itunes.apple.com/gb/app/os-gr...5554?ls=1&mt=8
Or search for "grid ref" in the app store on your phone.
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I also have a similar app available for use with the Irish Grid.
More information on OS Grid Ref Compass iPhone App