Thanks for the comments everyone.
There is a way to do this in Photoshop, but seems to not be a freely available technique.
http://www.prodigitalsoftware.com/As...l_Version.html
Looks like I'll just get the Green channel next time.
In the meantime have been having fun with a false colour version and some field rotation issues.
https://www.flickr.com/photos/johnka...blic/lightbox/
Clear skies.
John K.