I did everything again, this is what I did:

Power off printer.
cancel -a
Update to newest PPA - 1.5.3-0ubuntu2~ppa1.
Reboot computer.

On rebooting:

al@al-desktop:~$ date && cancel -a
Sat May 26 12:09:54 BST 2012
al@al-desktop:~$ date && sudo logrotate -fv /etc/logrotate.d/cups 
Sat May 26 12:10:01 BST 2012
[sudo] password for al: 
reading config file /etc/logrotate.d/cups
reading config info for /var/log/cups/*log 

Handling 1 logs

rotating pattern: /var/log/cups/*log  forced from command line (7 rotations)
empty log files are not rotated, old logs are removed
considering log /var/log/cups/access_log
  log needs rotating
considering log /var/log/cups/error_log
  log needs rotating
considering log /var/log/cups/page_log
  log does not need rotating
rotating log /var/log/cups/access_log, log->rotateCount is 7
dateext suffix '-20120526'
glob pattern '-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'
renaming /var/log/cups/access_log.7.gz to /var/log/cups/access_log.8.gz (rotatecount 7, logstart 1, i 7), 
renaming /var/log/cups/access_log.6.gz to /var/log/cups/access_log.7.gz (rotatecount 7, logstart 1, i 6), 
renaming /var/log/cups/access_log.5.gz to /var/log/cups/access_log.6.gz (rotatecount 7, logstart 1, i 5), 
renaming /var/log/cups/access_log.4.gz to /var/log/cups/access_log.5.gz (rotatecount 7, logstart 1, i 4), 
renaming /var/log/cups/access_log.3.gz to /var/log/cups/access_log.4.gz (rotatecount 7, logstart 1, i 3), 
renaming /var/log/cups/access_log.2.gz to /var/log/cups/access_log.3.gz (rotatecount 7, logstart 1, i 2), 
renaming /var/log/cups/access_log.1.gz to /var/log/cups/access_log.2.gz (rotatecount 7, logstart 1, i 1), 
renaming /var/log/cups/access_log.0.gz to /var/log/cups/access_log.1.gz (rotatecount 7, logstart 1, i 0), 
old log /var/log/cups/access_log.0.gz does not exist
rotating log /var/log/cups/error_log, log->rotateCount is 7
dateext suffix '-20120526'
glob pattern '-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'
renaming /var/log/cups/error_log.7.gz to /var/log/cups/error_log.8.gz (rotatecount 7, logstart 1, i 7), 
renaming /var/log/cups/error_log.6.gz to /var/log/cups/error_log.7.gz (rotatecount 7, logstart 1, i 6), 
renaming /var/log/cups/error_log.5.gz to /var/log/cups/error_log.6.gz (rotatecount 7, logstart 1, i 5), 
renaming /var/log/cups/error_log.4.gz to /var/log/cups/error_log.5.gz (rotatecount 7, logstart 1, i 4), 
renaming /var/log/cups/error_log.3.gz to /var/log/cups/error_log.4.gz (rotatecount 7, logstart 1, i 3), 
renaming /var/log/cups/error_log.2.gz to /var/log/cups/error_log.3.gz (rotatecount 7, logstart 1, i 2), 
renaming /var/log/cups/error_log.1.gz to /var/log/cups/error_log.2.gz (rotatecount 7, logstart 1, i 1), 
renaming /var/log/cups/error_log.0.gz to /var/log/cups/error_log.1.gz (rotatecount 7, logstart 1, i 0), 
old log /var/log/cups/error_log.0.gz does not exist
renaming /var/log/cups/access_log to /var/log/cups/access_log.1
creating new /var/log/cups/access_log mode = 0640 uid = 0 gid = 109
renaming /var/log/cups/error_log to /var/log/cups/error_log.1
creating new /var/log/cups/error_log mode = 0640 uid = 0 gid = 109
running postrotate script
compressing log with: /bin/gzip
removing old log /var/log/cups/access_log.8.gz
compressing log with: /bin/gzip
removing old log /var/log/cups/error_log.8.gz
al@al-desktop:~$ date && echo plug in printer
Sat May 26 12:10:23 BST 2012
plug in printer
al@al-desktop:~$ date && echo print a file
Sat May 26 12:10:57 BST 2012
print a file
al@al-desktop:~$ date && echo printed ok
Sat May 26 12:11:35 BST 2012
printed ok
al@al-desktop:~$ date && echo print it again
Sat May 26 12:11:53 BST 2012
print it again
-- THIS TIME IT DOES NOT PRINT --
al@al-desktop:~$ date && cp /var/log/cups/error_log ~
Sat May 26 12:12:24 BST 2012
al@al-desktop:~$ ls -lh error_log
-rw-r----- 1 al al 131K May 26 12:12 error_log
al@al-desktop:~$