REPLY Thank you Felix for your very informative answers. Being new to open source, I realize from your explanations that I have a lot to learn, like not allowing anything to install in the MBR, and taking steps to minimise the desruption and ease the recovery. At the moment I have no idea how!
I have just reinstalled 'grub customizer' in Ubuntu 16.04. Just like the previous version in 14.04, it did not see the Debian O/S. I assume because it's in an encrypted partition?? Thank you for quote and humour. Sorry some of my words are not so pleasant and persuasive!!! My 'open source' journey starts with a single bit step! Stefan Sent from [ProtonMail](https://protonmail.com), Swiss-based encrypted email.
