This paper is primarily concerned with a meeting that never happened and a letter that was never delivered. On the face of it, hardly a promising subject but one that is of far greater significance than it might, at first, appear. Sometime in the summer of 1682, just as a Moroccan ambassador was about to leave for home after a lengthy and successful visit to England,i some Unitarians in London attempted to deliver a bundle of papers to him. On hearing that they were concerned with religious matters, he declined to accept them, and so, unread, they passed into the hands of the Master of the Ceremonies, Sir Charles Cotterell, and from him to a Church of England priest, Thomas Tenison. When, over a decade later, Tenison became Archbishop of Canterbury, they found their way into the holdings of the library of Lambeth Palace, where they can still be consulted today.ii They rarely are. Indeed, the bulk of the material remains in the Latin in which it was originally composed. Although a few scholars have discussed this ‘curious case’,iii mostly in passing, and the occasional work of contemporary Unitarian literature does refer to it,iv though not always accurately,v the incident is largely forgotten.