How widespread was literacy in classic Greek in Europe during the medieval period? I assume "every" (?) educated person, such as clerks, monks, nobility, judges, doctors and similar knew Latin at the time, but how many knew classic Greek? By Europe I do not mean to include Byzantium. I am mainly referring to central, south and western Europe (todays Italy, Austria, Germany, France, Spain and UK).
Knowledge of Greek was rare until the Renaissance. Scholars fleeing the fall of Constantinople brought to Italy their knowledge of Classical Greek, a good bit different from the popular Greek.
In fact, through most of the Middle Ages, anyone knowing Greek was assumed to be Irish, and one of their better scholars at that.
The habit of making younger sons priests to hold the bishoprics or lesser benefices a noble family controlled often meant churchmen had little more learning than their secular relatives. Priests and monks with no real knowledge of Latin were not uncommon, doing their offices and prayers by rote.
The knowledge of Classical or Ancient Greek barely existed in Medieval Europe-(namely, Christian Western and Northern Europe), though it did exist within Islamic Spain. However, it was within Byzantine Constantinople whereby the maintenance of Classical Greek would have been widespread, primarily among the Clergy, as well as with Theology students studying at The University of Constantinople-(I know the question wants to address Medieval Europe regarding Classical Greek literacy, however, it is difficult to avoid mentioning Byzantium).
In the case of Medieval Northern Europe, Latin was the "Lingua Franca" among the Clerical and Scholarly elites. During the Late Middle Ages, If one was studying at a Theology school in Paris, Southern England, Northern Italy or Germany, Latin was the Central language. If one was professionally employed by the Roman Catholic Church-(regardless of rank), Latin, was the widely preferred and Central Language of textual, conversational and above all, liturgical literacy.
With regard to Medieval Islamic Spain, languages, such as Spanish, Ladino-(or Judeo-Spanish), as well as Arabic-(which was the dominant language at that time), were the common languages from Barcelona, to Granada, though Classical Greek was known and translated by Moorish and particularly, Jewish Scribes. However, for the Roman Catholic Christians of Medieval Spain-(both civilians and Clergy), Latin, was the Central Language of the Church.
Overall, it was Latin (and not Classical Greek), which was the preferred and universal language of the religious and scholarly elites within Medieval Europe,