In the ‘ Testimonium ’ prefixed to the ‘ Annals of the Four Masters ’, and signed by four Franciscan friars, the chief of whom was Bernardine O'Clery, guardian of the convent of Donegal in 1636, there is an enumeration of the principal sources from which the latter portion of the annals was compiled. The last-mentioned of these sources was the ‘ Book of Lughaidh Ó Clérigh ’, which the friars say covered the period 1586–1602. This book, we are to infer from the notice, was written in the form of annals. The other sources referred to are described in such a way as to show that they too were written in annalistic form.

The ‘ Book of Lughaidh Ó Clérigh ’, unlike some others utilized on the same occasion, has come down to us. It is now known as the ‘ Life of Hugh Roe O'Donnell ’, though that title does not appear in the sole authoritative manuscript. Indeed, the form of annals is preserved throughout, though it is not emphasized in the edition published by Denis Murphy in 1893.

Sir Thomas Phillips is not to be found among the worthies of the Dictionary of National Biography, nor is he mentioned in Webb's Compendium of Irish Biography or Crone's Concise Dictionary. He was one of those known in early-seventeenth Ireland as ‘ servitors ’—military men who had fought for the crown during Tyrone's rebellion and established claims on the royal generosity which they expected to have satisfied after the peace. In the Ulster plantation, servitors constituted a separate group among the planters, and some of them thus became the founders of great landed families. In his successful pursuit of forfeited land in Ulster, Phillips is a fair example of the servitor class. Very likely he would have left no more mark on Irish history than many another fellow-adventurer, had he not staked his claim in a part of Ulster that presently became a sphere of interest of the city of London. Within a few years of the Londoner's advent, Phillips engaged them in a controversy which he maintained with almost incredible pertinacity for a quarter of a century, and which, on the eve of his death, ended in a crushing defeat for his opponents.