Latin to English Social Sciences History Scientific Journal

I am reading about John of Doncaster, and Englishman who fought under Edward III in the Hundred Years War.
However, thre is not a conclusion about his social status, and some historians infer he was high born, while other don't.
In the Chronicle of Anonymous of Canterbury, a passage reads:

Postmodum uero unum ualettum Iohannem de Doncastre anglicum, apud Gynes per Gallicos incarceratum...

It was translated in the lastest version, published on 2008: An English valet, John of Doncaster, who had been imprisoned by the French...

Anyway, I would like to have a more detailed explanation on the word "ualettum", and if possible the word origin.