That images is as completed at the time. There was an original concept and model. The architect’s scale model of the original proposed building is considerably more ambitious in scale and treatment than the extension actually completed. This model, and the ground plans associated with it, show that the design was to have several turrets, not just the one octagonal turret.
I had read about the more ambitious proposals as part of the “Buildings” feature. Was the multi-turreted design featured in the scale model an illustration of the expanded College to include Scientific endeavours, or, simply a larger variant of the current building?
I never realised that this was built as a single building.
For some reason when looking at it, I’d always believed that the area right of the turret was older and that the turret and the area to the left was an extension.