high table

It is usually on a raised platform at the end of the dining hall, hence higher than the other tables.

high table (plural high tables)

1. A dining table for the use of fellows and their guests at certain traditional and prestigious academic institutions.
   • 1859–1861, [Thomas Hughes], chapter I, in Tom Brown at Oxford: […], part 1st, Boston, Mass.: Ticknor and Fields, published 1861, →OCLC, page 12:

     No one feeds at the high table except the dons and the gentlemen-commoners, who are undergraduates in velvet caps and silk gowns[.]