Spanish term (edited): la Gram�tica de Lebrija

If you are looking for something related to grammatically-orientated language teaching which has gone out of fashion, which was general knowledge for reasonably educated people of an age with those educated in the last days of Franco (did anyone younger than about forty in Spain ever hear about Antonio de Nebrija at school?), I think this is a good match. The "text book" which was usually used with Kennedy was "Hillard and Botting", but although the name has a ring to it, it has not been re-published relatively recently, unlike Kennedy.
Yes, I know it has nothing to do with the Renaissance, the School of Toledo, or vernacular grammars, but then I don't think there was any widely-remembered grammar of English published in the late 15th century. (By the way, what an amazing year 1492 was for memorable events!)

If you are looking for something purely related to English as a foreign language, what about "L.G. Alexander"?

Another point, not relevant to your solution, is that this is the first time I have seen this as Lebrija, and not Nebrija. Elio Antonio de Nebrija (Antonio Martínez de Cala) was indeed from what is now known as Lebrija, but the reference books all seem to stick to the earlier version of the name, since the grammar was published as by Antonio Nebrissensis.