O'Brien rose to be quite senior, serving as private secretary to Seán T. O'Kelly (a minister and later President of Ireland) and Seán MacEntee, a powerful political figure, both of whom almost certainly knew or guessed O'Brien was na gCopaleen. Though O'Brien's writing frequently mocked the civil service, he was for much of his career relatively important and highly regarded (civil servants designated to private secretary to ministers are usually considered "high flyers" and expected to rise to very senior roles in government) and was trusted with delicate tasks and policies, such as running (as "secretary") the public inquiry into the Cavan Orphanage Fire of 1943 and planning of a proposed Irish National Health Service imitating the UK's, under the auspices of his department - planning he duly mocked in his pseudonymous column.