St Mary the Virgin, Saxlingham Nethergate — Conservation of Medieval Stained Glass

St Mary the Virgin, Saxlingham Nethergate is a medieval Norfolk church containing stained glass of considerable historic importance. The chancel windows had been released by G. King & Son in the 1970s, but the medieval glass itself had suffered from surface corrosion — an accumulative deposit of mineral salts that forms on ancient glass and, if left untreated, can obscure and eventually destroy the original painted surfaces.

A previous attempt to address the corrosion in the 1970s involved grinding away the deposit — an approach now understood to be damaging, since it also removes the natural patina that forms a protective skin over the glass surface. Within twenty-five years the glass had developed a new corrosive deposit, confirming that abrasion is not a long-term solution.

Devlin Plummer's conservation approach takes a fundamentally different position: respecting the glass's natural protective surface layer rather than removing it, and applying reversible conservation consolidants where the glass is at risk of structural loss. This philosophy — derived from current best practice in stained glass conservation science — ensures that the medieval glass is preserved in the most authentic and stable condition possible for future generations.