I am a clumsy user. I press the enter key before the system has recognised the disk (a slow drive). Unfortunatly the Script terminates and I loose it all. Rather than rewrite an entire routine to better handle the burning process and associated errors rewrite the growisofs to write appropriatley sized iso files for later burning also allows more flexibility. I will try this myself but I have my doubts that this is the ideal starting point for someone with my Python skills.....
Thankyou for this excellent script