After adding the chainloader +1 statement to Linux Grub I managed to actually boot into the PTR based Grub of BeleniX anyway ha ha ha - ah what a day and what an amount of hacking but great recovery!!
The system is now bootable! It seems that BeleniX wipes the MBR upon install so then when the partition (not slice!) that it resides on is set with the bootable flag, the Grub loader is automatically found in the PTR and booted. So to reverse re-install Linux Grub as suggested above then chainload to PTR based Grub and all is ok. Enough posting for today I'm off!!! Yaaaaawwwwwn......
