After the fire of 1270 , a programme of reconstruction was launched , with repairs and a major enlargement . Outer aisles were added to the nave , the eastern wing comprising the choir and presbytery was doubled in length and had aisles provided on its north and south sides , and the octagonal chapterhouse was built off the new north choir aisle ( Figs . 8 & 9 ) . The new northern and southern aisles ran the length of the choir , past the first bay of the presbytery , and contained recessed and chest tombs . The south aisle of the choir contained the tomb of bishop John of Winchester , suggesting a completion date for the reconstructed aisle between 1435 and 1460 ( Fig . 10 ) . Chapels were added to the new outer aisles of the nave and were partitioned from each other with wooden screens . The first bay at the west end of each of these aisles and adjacent to the western towers did not contain no chapel but instead had an access door for the laity .