The oldest stained glass in the Cathedral, the Becket Window is an extremely fine example of early 14th century glass.
The striking tracery glass in the upper half of the window is particularly notable for the centre panel which shows the martyrdom of St Thomas Becket which took place in Canterbury Cathedral in 1170. The four knights of Henry II, who carried out the martyrdom, are shown to the right of Becket who is kneeling in front of an altar. Behind the altar, with hands raised, stands Brother Grimm, the monk who witnessed the killing. Such images depicting Becket were very common in medieval windows but are today extremely rare, owing to their destruction by Henry VIII in the 1530's.
This panel survives only because someone had the foresight to remove Becket's face, replacing it with a pear-shaped piece of clear glass. This in turn was replaced by a modern piece of pink glass by the York Glaziers Trust who carried out a complete restoration of the window in 1981. In recommending this work PA Newton of the Trust stated; 'I would suggest, particularly as otherwise this panel is a very complete and extremely important survival of the Becket iconography, that the present glass occupying the head space should be replaced by carefully selecting pink glass stippled to tone with the heads of the knights and Grimm. The stippling could give a general indication of the main features, hair, nose and mouth etc, but I would not recommend any attempt to 'reproduce' a detailed piece of painting.'