Angle between the upper north transept and choir

Unlike the nave, the choir has double aisles, necessitating an intermediary upright to support the flying buttresses as they pass over the outer and inner aisles. It will be remembered that at ground level the intermediary piers dividing the choir aisles are very slender. There was no question of using the same massive solid flyers of the kind we found in the nave. Here a single intermediary upright receives the thrust of flyers supporting the upper transept and the upper choir: that enormous weight is delivered to the slender pier below. It is not surprising that this arrangement has caused considerable problems necessitating the reconstruction of aisle vault and piers below