The ambulatory extension walls, or ‘wing walls’, will continue the ambulatories from the Chancel into the new Bishop Selwyn Chapel. The taller of these concrete walls will be over 8 m high to match the current parapet level of the existing ambulatories. The lower third of each wall has been cast in situ. The upper two thirds have been manufactured off-site in a factory as pre-cast slabs. The photo below shows one of the slabs undergoing a finishing sand-blast treatment.