This is software I have written in the past which is available for download.
The link below leads to a program I wrote (a long time ago), which will convert between British National Grid References ( NGR ), Latitude and longitude (which can be specifyed as either minutes and seconds, or a decimal value), Maidenhead locators (also known as IARU squares) and WAB squares. It works within the area of The British National Grid.
The program is dos based. Providing you follow the syntax for entering the input you are entering, the program automatically works out what type the input is.
Just click the link to download, select 'save to file' and then
execute the file.
Download locator
This software is free for non commercial usage, providing
it is not modified in anyway. You may not distribute it in any way,
but feel free to point people in the direction of this website.
Although the program has been heavily tested, I can't take any
responsibility for what you do with it after you have downloaded it.
Don't rely on it for anything important.
I have been meaning for a while to rewrite the program into a java or C (or similar) library and open up the source code. I've just never got around to it. Or I might try seeing if the original Turbo Pascal source code will compile under a linux pascal compiler.
Please email me with any comments.