Thomas Bourchier (pronounced Bowcher) 1404-1486 was a grandson of Edward III held a variety of senior posts (Chancellor of Oxford University, Bishop of Worcester and later of Ely) before becoming Archbishop of Canterbury in 1454. He became a Yorkist supporter and crowned Edward IV in 1461. The tomb has no effigy and was designed to allow light to shine through to the area of the altar. Its Purbeck marble chest appears exceptionally high when viewed from the north aisle (as in the photo) but this is mainly to compensate for the higher floor level on the Sanctuary side.
What to see:
a massive chest of Purbeck marble topped with a high canopy of Caen stone (Image 1)
the rebus of butcher's knots (the French for butcher is boucher, and anyway butcher sounds like Bowcher) can be seen here in various forms on the stone work, together with a second rebus of twigs and leaves depicting 'Woodstock', the family of Bourchier's mother, Ann of Gloucester (Image 2)
Bourchier was a patron of the rebuilding of the Dean's chapel - the family knots are repeated in the stained glass here (Image 3)
Sources: see standard cathedral sources