Heritage aluminium windows, Merchant Taylors' School

The windows that came out were Crittall and they were in poor condition. Steel windows of that age tend to go the same way: the sections corrode, the frame distorts as they do, and a point arrives where there is nothing left to repair. These had reached it, so the run came out rather than being patched again.

The school dates from 1561, which decided what went back. The brief was to keep the look of the elevation rather than modernise it, and heritage aluminium is what answers that: slim sightlines and horizontal bars that read like the steel windows they replace, in a material that will not corrode the same way. Each opening keeps its own proportions, so the run still reads as it did from the ground.

The windows are Sheerline, finished in HIPCA white, RAL 9910. The glass is laminated throughout, and in the changing room it is Arctic obscure, so the room takes daylight without giving anything away from outside.

It ran in term time and the fitting took a couple of days. That is what a straight replacement into existing openings buys you: the brickwork is untouched, the reveals stay as they are, and the disruption to a working school is measured in days rather than weeks.