
PHOTO: GREGOR RICHARDSON
Mr Mackenzie said he felt the pressure to remain calm and accurate when dealing with the "irreplaceable treasures".
"You have to judge with extreme finesse the amount of pressure you can apply and where you cut into things."
He said the church’s neo-gothic architecture was incredibly elegant and it was a privilege to work on the windows.
"We could see a lot about how it was built and just how much incredible craftsmanship had gone into every aspect of it, even parts of it that the public normally wouldn’t see."
After his work the light levels in the church had improved by at least 20%, he said.
The church will be open to the public tomorrow for the first time since January.