Well yes, why wouldn't Irish people trust a British writer, unless they are mired in bigotry? Surely you're not suggesting Irish people are too prejudiced to trust a British writer? That's very disturbing as the British have held Irish writers and literature in high regard for a very long time, despite the politics of the last 200 years.
You may not be familiar with Sebag-Montefiore then but he is highly regarded. Here are some of his awards. Catherine the Great & Potemkin was shortlisted for the Samuel Johnson Prize, the Duff Cooper Prizd and the Marsh Biography Award Stalin won History Book of the Year at the 2004 British Book Awards. Young Stalin won the LA Times Book Prize for Best Biography, the Costa Book Award ,the Bruno Kreisky Award for Political Literature, Le Grand Prix de la Biographie Politique and was shortlisted for the James Tait Black Memorial Prize.
Jerusalem: The Biography won The Jewish Book of the Year Award from the Jewish Book Council.
One Night in Winter won the Political Novel of the Year Prize and was longlisted for the Orwell Prize