Ok - just thought of something and it seems my hunch is right - it was never the original 'Mac OS X 10.6.8 update' that caused me the problem in the first place, it was Apple's 'Epson printer software update 2.7' ... so I checked the order of the latest updates installed ... it seems the 'Epson update 2.7' intalled again after the 10.6.8 supplemental update so no wonder printing was not working!
I've just tried installing the 10.6.8 suplemental update 1.0 again and this time printing still working fine - checked the date of the IraMW1 file and is still the older one that works.
Very brief version of my Apple update history since this all began:
• Installs Apple's Epson 2.7 update then Original OSX 10.6.8 update = Fails to print
• Tries all sorts then finds fix by reverting the IraMW1 file to an old version from a backup and printing is fine again
• Installs Apple's Epson 2.7 update again = Fails to print so I revert the IraMW1 to the old version and printing is fine again
• Installs OSX 10.6.8 supplemental update 1.0 then Apple's Epson 2.7 update = Fails to print so I revert the IraMW1 to the old version and printing is fine again
• Installs OSX 10.6.8 supplemental update 1.0 again = Prints fine
Should be pretty obvious by now that it's Apple's Epson 2.7 update causing the issue not OS X 10.6.8 ... for me at least!