William Postard was Abbot of Westminster from 9 October 1191 and had been Prior under Abbot Walter. He died on 4 May 1200 and was buried in the south cloister of Westminster Abbey "before the cymbalum (bell) which was sounded for meals in the Refectory", which was the west end of this cloister. No inscription now remains for him but it was recorded as (translated from the Latin):
"William Postard is buried in this ground: in this place he was Father, Pastor and previous Prior".
The monks passed over Henry Longchamps, brother of the Chancellor, in favour of electing Postard as Abbot. He granted to the monastery his vill of Parham. During his abbacy he allowed the bishop of Exeter, Henry Marshall, to erect a chapel on some land on the Abbey's estate at Longditch. He gave money towards the maintenance of the Abbey infirmary (this was in the area of the Little Cloister).
The illustration is of the reverse of the Abbot's seal from a document in the Abbey archives, showing the head of a king.