How can I convert OSGB36 to latitude / longitude co-ordinates using VBA?

I have to calculate distances between map points as开发者_如何学编程 part of a project I am doing. The map points are provided in OSGB36 co-ordinates, e.g. 508800 / 181100 (being easting and northing). I have come across many functions to calculate the distance between 2 lat / longs and so would like to convert to these using VBA within an MS Access database.

Does anyone know how I can do this?

Thanks, Steve

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Rectilinear coordinates like this actually need nothing more than http://en.wikipedia.org/wiki/Pythagorean_theorem to calculate distances.

$d = sqrt(pow($e1-$e2,2)+pow($n1-$n2,2));

Where $d is the answer in meters. $e1,$n1 and $e2,$n2 are your easting/northings of the two points.