UK licence categories with a code 1 or 101 are not accepted when exchanging a UK driving licence for an Irish one, as per the Memorandum of Understanding on the exchange of driving licences agreed between Ireland and the UK.
Some UK categories known as ‘National Categories’ [similar to our W Tractor] only apply in the UK and they are not exchangeable. Other categories may be given with restrictions identified by codes. These categories with national codes are valid only for driving in the territory of the issuing authority. For example, in the UK if you passed your test for category B (car) before 1 January 1997, your licence would show entitlement D1 and D1E (bus) categories with a restriction code of 101. The D1 and D1E categories with a restriction code 101 only allows the driver to drive a vehicle not for hire or reward. We do not have the corresponding category and so cannot exchange it.