KT84 seems to have forgotten that Ireland ceased to be part of the UK over 80 years ago ;-)
The TCD admission requirements are here:
http://www.tcd.ie/assets/documents/other/admis sion_requirements_2007.pdf
The 'minimum points' column indicates the lowest qualifications with which students were admitted to that course in 2005. The points scoring system is similar to that used by UCAS. The equivalent Irish body is the CAO:
http://websr4.cao.ie/APP/index.php
While all UK HE subscribe to the same points scoring system for Irish qualifications, they don't all agree to use the CAO scores for overseas qualifications (such as A-levels). TCD is one institution which doesn't directly subscribe to CAO scoring for A-levels but it's likely that you can get a good guide to their requirements by using the pdf, above, and the CAO information, here:
http://websr4.cao.ie/APP/index.php?page=scorin g&s=gce
Chris