Sorry, cant get into the DT, for some reason, cant check version. The verse quoted is currently sung at Queen's as:

The boars head as I understand
Is the rarest dish in all the land
Which thus bedecked with a gay garland
Let us servire cantico.

I think this is pretty old, though the spelling is modernised. Cant give you chapter and verse for how old, the language looks around 1600??