Just made a rookie mistake by updating to ubuntu 17.04 on this machine. - lost boinc installation and had to re-install. Time to go and dig out how to tell boinc where to store data! - On previous installations I have usually gone for the discrete version which then ran from my home directory. More recently I swapped to the packaged version which is for some reason more up to date than the one from the BOINC download page, but didn't think to back all the data before doing the upgrade so 3 561's and a couple of others lost though it looks as if most of the 561s on linux might have crashed anyway.

3rd install screen for BOINC, bottom right corner, Advanced.

Thanks Les, I have found where to do it after installation. - the install screens don't come up when installation is done via the package manager.

Edit:

Instructions I found as follows.

Move your Linux machine’s BOINC data directory like this:

1. sudo service boinc-client stop
2. sudo mv /var/lib/boinc-client/* /path_to_new_dir/boinc-client/
3. sudo rm -rf /var/lib/boinc-client
4. sudo ln -s /path_to_new_dir/boinc-client /var/lib/boinc-client
5. sudo service boinc-client start

Except that I stopped and started computation via the gui.