Further to my earlier post at http://geekswithblogs.net/TATWORTH/archive/2014/06/18/style-copping-the-c5-collections-project.aspx
SubMain have come back to me with a fix for the rules file for GhostDoc Pro which will be incorporated in the next release. I was able to apply the fix to the rules file using the GhostDoc options dialogs and GhostDoc now correctly documents the errant routine.
JetBrains have classified my report (http://youtrack.jetbrains.com/issue/RSRP-416534) as a Show-Stopper.