Work on the Herkenrode windows begins in earnest on Monday 20 July. In the first week, a fire-proof screen will be erected at the west end of the Lady Chapel, sealing off everything east of the ends of the quire aisles, from floor to ceiling. After Sunday 19 July it will not be possible to enter (or even see into) the Lady Chapel for a period of up to eighteen months. It will not be possible to use the Lady Chapel for worship during that time, and visitors will be unable to view (for example) the Selwyn Memorial.

Why is necessary to close the Lady Chapel?

The sixteenth century Herkenrode windows in the Lady Chapel are one of our Cathedral’s great treasures. They are a brilliant example of renaissance stained glass and have international significance. But the glass is in urgent need of conservation and the Lady Chapel stonework is in equally urgent need of restoration and repair. The scale of the work is so great that there is no option but to close the Lady Chapel.

What’s the matter with the glass?

The great enemy of ancient painted stained-glass is moisture, which causes paintwork to erode and fade. The glass (which was installed in our Cathedral in the early 1800s) has deteriorated badly over the last 200 years. The plan is first to undo some of the effects of this deterioration, and also to prevent further deterioration in future.

What will happen to the glass?

This is a programme of conservation, not restoration: so there will be no attempt to re-paint the glass where it has faded. Instead, to undo the effects of past deterioration, the glass will be cleaned piece by piece. Over the next few months, it will be removed panel by panel. It will be photographed and catalogued, and then crated up for secure storage. Over a period of several years each piece will then be carefully cleaned by one of the foremost firms specialising in this sort of work. The cleaning will remove deposits of pollution and dirt and will leave the glass looking much fresher and brighter.

In a few cases, it is likely that, using a technique applied to the back of the glass (ie, not on the painted surface), some lines will be etched to restore a bit of detail especially to faces, to help viewers to ‘read’ the glass more fully than is possible at present. Then the glass will be re-installed, but in front of a layer of ‘iso-thermal’ glazing, to protect the glass from the harmful effects of condensation in future.

What will happen to the stonework?

Once the glass has been safely removed from the windows, work will begin on the restoration of the Lady Chapel stonework. The ‘mullions’ (the narrow vertical pillars of masonry which separate the panels of each window and help to take the weight of the lead and glass) are in a particularly parlous state. Once the stonework around each of the seven windows is repaired, the window will be filled with clear glass. When that work is complete (some time before Christmas 2010), the Lady Chapel will return to use.