Not considering Norn Iron as "British" is parts of the Graun's agenda.
How can it be part of an 'agenda' to state something which is factually correct. Northern Ireland is part of the UK, it isn't part of Britain.
To imply that a bomb blast in Belfast was on British soil would be simply incorrect - if a newspaper did that it might be due to ignorance on the part of the article writer, or due to an agenda, but it is hard to see how being factually accurate (as the Guardian article was) is evidence of some agenda.