Converting Ordnance Survey Grid Ref's to Lat/Long's

[Martinburney]

Hi All

There is a difference of opinion, which is the best programs to use, when converting from Ordnance Survey Grid References to Latitude / Longitude References, without referring to the Ordnance Survey Maps.

I am using multimap, which I personally feel suits my need, but it has been pointed out, that it is not totally accurate.

There are other systems available.

Would anyone recommend any other system, that they use, or is the only true accuracy, the various Ordnance Survey Maps published.

Regards Martin Burney

[Keef]

Some years ago, with assistance from the OS, I wrote an Excel routine which will convert Lat/Long to NGR or vice-versa. It's incorporated into the A4A Airfields list (I use it to check for duplicates, among other purposes).

It's accurate to ten metres or better on the WGS84 geode. With changed constants, it will work on any other geode you prefer to use.

I think it's on the CD I sent you, but if not I can soon e-mail that bit to you.

I think most of the "mapping" programmes have a facility to display NGR and Lat/Long or both, but I found that too fiddly when i wanted to check a list of references, and sometimes the answer one map gave was clearly wrong.