This record is from The Cartulary of Newnham Priory, transcribing a record from 1166. Simon [II] de Beauchamp granted whole churches and fractions of other tithes to Newnham priory. Here is how it was written:
Concessi eciam eis has decimas, scilicet duas partes decimarum in molendinis et pannagiis et in ceteris dominiorum de Stotfolde, de Hagenes, de Kaishoo, de Lincelade, de Euersholt, de Hunesdone, de Puttenho, de Calworth', de Asple, de toto feodo meo in Holewelle.
This must have been a precisely-understood account, because it's a valuable gift. Elsewhere the priory records gifts down to the farthing. But various modern interpretations of this text online and in print quote differing fractions for the gift. Here's a straight google translation:
I have also granted to them these tithes, namely, two parts of tithes in mills and pannages and in the other lordships of Stotfold, of Hages, of Kaishoo, of Lincelade, of Euersholt, of Hunesdon, of Puttenho, of Calworth, of Asple, for all my fee in Holwelle.
But google also translates
scilicet duas partes decimarum in molendinis et pannagiis as
namely two-thirds of the tithes in mills and pannages. And also translates
duas partes decimarum as
My understanding is that the tithe in mills and pannage should be one tenth of the total produce. So two thirds of that would be 6.67% of the total produce. Or two tenths would be 2% of the total produce. This must be a precise definition, but just what is the number, please?