Richard Leighton Greene says in The Early English Carols, 2nd ed. (Oxford, 1977, No. 11 [notes, p. 345]):

   The carol is written as if to be sung by a master of festivities or 'Lord of Misrule' with power to 'punish'. The obligation of each person present to contribute to the general entertainment is characteristic of many English holiday customs. Compare No. 10.
   stza. 1, l. 2. The marshal of a medieval hall had the duty, among others, of seating the guests at any feast. A groom served under a marshal, building the fires and performing other practical tasks in the hall. See F.J. Furnivall, ed., The Babees Book (E.E.T.S., Or. Ser., No. 32, 1868) for The Book of Curtasye, Bk. III, ll. 379-422, which deal with the marshal.
   stza. 3, l. 3. stokkes. R.J. Schorck rightly calls attention to the use of actual stocks at the order of a Lord of Misrule at Christmas (review of Robbins, Secular Lyrics, Anglia, lxxi, 1953, 356). See Chambers, M.S. i. 408-9 for instances at Oxford colleges.