@yancek. No I don't think it was the safe mode entry. One was generated as I surmised by Ubuntu seeing the Linpus load, the other was my entry I put in the Custom file.
The reason I know this is that I had to rebuild 11.04 yesterday due to a different issue with the Unity desktop and have now established that if you manually mount the Linpus partition prior to a update-grub then the partition is found and the Grub2 menu updated. If its not mounted (as is the condition during the standard install process) then for some reason the Linpus instance is not seen.
@RockDoctor, don't berate yourself mate ;-)
I learnt a lot going through your instructions and now have a better understanding of how the Grub and Grub2 work as a consequence. So my thanks are still valid. Cheers.