Kay / Cai

'In medieval Welsh law the revenue officers were termed Cais. The word is formed from ceisio, to ask, seek, search for, and is the linguistic equivalent of the Latin erogator, 'a person who asks' for revenue on behalf of the state. Like the erogator, the cais visited each district in turn to collect it's stated tribute...The term cais was commonly Englished as Keys or was translated by serjeant; and the serjeant made similar circuits, collecting cornage, cowgeld and maintenance.' - The Age of Arthur - John Morris