Anyone in public life can expect to have their integrity, capacity and even family scrutinised, challenged and impugned.
Politicians, like racehorses, carry handicaps, some they grew up with and others of their own making. The more prominent, the more questions they face. Everyone sits regular examinations, with extra papers in their own area of special difficulty.
The conspiracy theory is a great weapon. Considerable political (and journalistic) time is given to testing out conspiracy theories, and trying to stand them up. If plausible, or partly true, they lead to tribunals and inquiries, even crises. Few victims are entirely innocent, in terms of never believing conspiracy theories about others, including newspapers.
My first article for The Irish Times stirred up latent paranoia. "Mansergh sleeps with the enemy" was the headline in the Phoenix (26/9/03). Described as "hardly the most republican forum in the media", the paper isn't the least republican either.
For praising the Irish Times Trust, which keeps at bay wealthy proprietors with the power to hold governments to ransom, I drew down the wrath of two fertile local historians of the North Cork Aubane Historical Society. An angry letter from Jack Lane is circulating in print, with Brendan Clifford asking what I was up to (Northern Star, March 2004).
Clifford depicts The Irish Times as the "Irish" newspaper acceptable to Downing Street. No doubt, someone there scans The Irish Times, as they do Le Monde, but no one on the paper has featured recently in the British honours list.
"Proof" of a conspiracy operating to this day is a report by the British ambassador, Sir Andrew Gilchrist, in October 1969 about conversations with an Irish Times board member, Maj Tom McDowell, who apparently complained, using an appalling racial metaphor, of the renegade editorial line of Douglas Gageby on the North, while seeking guidance from Downing Street on lines to follow.
I interpret that differently as editorial control slipping away from a deeply conservative old Protestant business class that still looked instinctively to England, in a new Ireland post-Lemass facing into the Troubles.
As for the Trust, it was reformed before I started writing for the paper. A few years ago The Irish Times quarrelled with attempts by Lane and Clifford to excise Elizabeth Bowen from every canon of Irish literature or identity, in complete defiance of pluralism.
A distant relation of my father by marriage, she was (mostly) proud to be Irish and is remembered annually at Farahy Church near Kildorrery, of which I am a trustee. Though distasteful, her wartime "spying" activities were about as sinister as any by John Betjeman.
It was probably fortunate to have working for the British administration during the war Irish people who understood neutrality was necessary, and whose analysis helped others restrain Churchillian aggressiveness. They included my father, who was cleared by Joe Walshe, secretary of the Department of External Affairs, to work in the Ministry of Information, where Shevawn Lynam and Rita Dudley, later President Childers's wife, also worked.
If one comes from that diminishing Protestant sub-class, those of Anglo-Irish background; was born in England; and educated at public school (only a minor public school, King's School, Canterbury, as Senator Shane Ross points out), decades of Irish public service will not dispel every single lingering suspicion.
The question was put to a noted Irish-speaking historian from Galway by friends some time ago: "Can we trust him?"
Or, as a former Fianna Fáil minister, quoted in Kevin Rafter's biography, asked (with a laugh): "He was educated at Oxford University, right? Well, then you'd have to ask, who does he work for?"
An editor telephoned me in 1987 with a bizarre story from the previous government. Two ministers told Peter Prendergast, the government press secretary, they had reason to believe I was an MI6 agent, asking him to find out more.
Imagine. At a time of tension over Northern policy it might, if true, have discredited the leader of Fianna Fáil the Republican Party as brilliantly as the exposure in 1974 of an East German spy, Günter Guillaume, in the private office of the Chancellor, Willy Brandt.
I reported to the taoiseach, Mr Haughey, how I was being maligned. He looked up, laughed and said: "Join the club".
A couple of historical experiences that ended unhappily created some wariness of cultural difference in nationalist politics. Controversy over Parnell's love for a married woman wrecked Home Rule, though it would be absurd today to regard the private morals of a non-Catholic as a particular political risk factor.
Erskine Childers snr wrote a famous spy novel, The Riddle Of The Sands, credited with fuelling the naval arms race before the first World War, and was a wartime military intelligence officer. Yet as a skilled yachtsman he was central to the Howth gun-running, and a brilliant propagandist during the war of independence.
A conscientious opponent of the Treaty, he was accused of being the godfather of republican anarchy and a British agent out to wreck the Free State. The fact that Churchill gloated over his execution, the high esteem Childers was held in by de Valera and Frank Gallagher, and no evidence to support conspiracy theories only highlight the tragedy. The Wicklow TD and Minister of State, Dick Roche, has successfully pressed for his portrait to hang in Leinster House.
People rarely think calumny through. To be one's whole adult life the agent of a neighbouring country, one would need to be a consummate actor and unblushing liar, calmly deceiving family, friends, colleagues, and neighbours.
Supposing a desire to serve Britain from conviction, then the straightforward course would have been to join the British civil service or a political party.
A belief that I, and more belonging to my tradition, should serve Ireland brought me home over 30 years ago. I have enjoyed great trust, so I am not intimidated by the thought that conspiracy theories, like empires, strike back.