After a suggestion from a colleague who had the same issue, I tried "apt-get remove perl" from a root session. It said that a package called something like 'wpa-key edit' depended on perl. I then quit and uninstalled wpa-key edit from the app manager.

After that, the update installed smoothly.

I don't recall installing wpa-key edit (but I might have forgotten) - any one any idea what it might be for and why I might need it?

Rgrds

F