NIKON D70 - 1/500 sec, f4.2 at 38mm
Darren, it's even easier than we thought, which is why we couldn't figure it out.
* Destaturate the image - Images / Adjustments / Desaturate
* Then select the history brush, and paint the color back in, keep between the lines, you'll need to zoom in
* Crop as required
Now lets see you do it!