Dave Baker wrote:

A couple of months ago I briefly unplugged my faithfull old HP Laserjet 4

Not a high end version with internal hard drive by any chance?

flashing a few lights on and off and booting up fully it printed out a sales
invoice of mine from 1995!!!!!

The only other obvious cause would be something sat in the spool queue,
possibly printed by accident, that was printed some time when the
printer was offline.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/