Dear Mikkel and Colin,
Thank you for the question and the prompt reply. I have hastened to add your link Colin to the page on my WEB-site, which deals with the grid systems used by the various services of the nations involved in WW II. Please see:
http://www.gyges.dk/reporting_grids.htm
It would be of great value if someone could provide a link to a site, which explains the system used by the Royal Navy.
brgeds
SES
www.gyges.dk