The south west tower was rebuilt in the 1450s, designed by Thomas Mapilton but constructed under the supervision of master mason Richard Beke. It matched the nave in style and was given substantial buttresses in order to cope with the weight of the bells transferred from the raised Bell Harry. Seen from within, the impressive fan vault ceiling includes a wooden trap door used primarily for the raising of bells - the earliest the huge St Dunstan bell put in place in 1459. This tower is also known as the Chicheley, Dunstan, St George's or Oxford tower (Chicheley was founder of All Souls Oxford).
What's of interest:
south west tower built 1450s to match perpendicular style of the newly completed nave (Image 1)
pinnacles re-fashioned in the 1920s under the direction of Cathedral architect W D Carőe - the modernised almost art deco style did not please all (Image 2)
the clock on the south west tower (Image 3) relies on the massive Great Dunstan bell to ring each hour - re-cast on several occasions, the present version was installed in the 1760s by the team of 34 strong men chosen to lift the weight (over 3 tons) into place
fan vault ceiling and trap door used for raising of bells (Image 4)
Sources: Bell (2009)