"
I sucessfully downloaded the bz2 package from sourceforge
I then sudo a nautilus session and unpackaged into /opt/calibre
done.
Note that my metadata.DB was already at the 6.44 level" quote theducks
Thought I'd have a go at this and I managed to install it but I took the long way round! (my knowledge of shell commands is terrible!)
In case it might help someone else - I downloaded the .bz2 and converted it to deb file using "alien" (install from synaptic and then in a terminal type "sudo alien --to-deb <path to file>"). I then installed the deb file successfully but the program wasn't included in the applications list

Had a brainwave then and simply added it to the startup applications! So now when I start ubuntu I have the new version of calibre sitting on the desktop

Im absolutely sure there is an easier way to do this but this worked for me.
I hope I don't have to do this with every new version!!