I've been contributing to a discussion on Politics.ie over the term West Brit. As usual the discussion is heated especially among those who live in Northern Ireland.
The meaning of a term lies in it's usage. West Brit is a prerogative term used by people accept a romanticized narrative to construct their Irish identity. Irish people who do not share this narrative are then excluded from self-identifying as being Irish, or at least, as being truly Irish. It is sufficient to merely disagree with an Irish nationalist over a topic such as the Irish language to be labeled a West Brit.
The term is very similar to the McCarthyist tendency of using the "communist" label for anyone or anything not deemed to be sufficiently American, regardless of whether they were related to communism or not.
Identity is a paradoxical concept. The Latin root of the word (idem) means 'same as'; we share common identities with other people. But on the other hand, the word also represents differences. To say you are Irish is to say you are not English or French. English and French are excluded from the Irish identity narrative*. Identity then represents a groups uniqueness and their difference from other such groups. The differences to an outside may appear completely trivial but historically groups are willing to fight and die over such trivialities.
A West Brit then is an Irish person who is judged to support English culture over Irish culture; they judge English culture inherently superior to Irish culture. As one poster put matters: "West Brits regret not being born English". Another poster provided a more extreme definition:
A west Brit (for me) is someone who is not from a Unionist tradition but who wants to undermine the Irish state and traditions, disparage our independence and re-unify with the UK.
In other words to label someone a West Brit is to label them a traitor to the Irish state. This however is an extreme definition. More common definitions involve some theory of post-colonial inferiority complex: Ireland was colonized by Britain for over 800 years leaving Irish citizens with a subconscious political outlook that is ultimately West British and contemptuous of traditional Irish culture.
Psychologizing arguments is always a convenient move but it shifts the debate towards personal character traits and as such it is a form of an ad hominem attack. In other words if you disagree with an Irish nationalist over a point of Irish culture, you are not simply mistaken but psychologically damaged by subconsciously internalizing an imposed imperial culture which is then repressed. That a person will always deny being a west brit is then viewed as further proof of this repression.
This claim is postmodern and relies on the mystical ability to peer inside the true soul and spirit of the writer of the text. It is claimed a person is motivated by a subconscious political outlook that is ultimately west British. But as this outlook is subconscious, it is never explicitly stated but can be inferred from a rejection of certain Irish identity narratives. The truth or otherwise of statements is never considered.
In summary, 'west brit' is a prerogative term used by Irish nationalists to label Irish people who disagree with their narrative of national identity and caused by either subconscious post colonial trauma or outright hostility to the Irish state.
*Yes, for the sake of simplicity I am ignoring more complex Anglo-Irish identities.