For more than 80 years a factory off Norwich's inner ring road carried out painstaking work which means many of the most beautiful stained glass windows in the country are as resplendent now as the day they were installed.

And a window into the remarkable work which went on at G King and Son has been opened thanks to a new exhibition which charts the company's legacy.

The working methods of Dennis King, hailed as an outstanding restorer of medieval stained glass, are explored in a new exhibition at The Archive Centre in Norwich.

Projects featured in detail include the restoration of the medieval 'Tree of Jesse' window at Winchester College, the conservation of glass in East Harling church and in Norwich Cathedral and installations of new stained glass windows at the church of St Thomas, in Earlham Road.

Also on display is a coloured design for a window depicting 'Agriculture', dominated by a huge red tractor, which was drawn up for a new Johannesburg Stock Exchange building in the 1960s and is one panel in a wall of stained glass windows depicting industries which created the wealth of South Africa.

Derrick Murphy, leader of Norfolk County Council and chairman of the Norfolk Records committee, said: 'This is one of the largest collections at The Archive Centre and is a comprehensive record of a little known but fascinating craft.

The breadth of G King and Son's work is quite incredible – there can scarcely be a church building with stained glass of any significance, particularly of the medieval period, on which King and Son did not work or advise.'

The company, which was founded in 1927, originally worked on pubs and cinemas, but by the 1930s it had started restoring ecclesiastical glass.

It became the leading stained glass conservation company in the country, working on glass at Great Malvern Priory, Wells Cathedral, King's College Cambridge, Norwich's own St Peter Mancroft and York Minster.

The company was wound up in 2003 and the archive was almost shipped out to the United States of America in 2004, but received a reprieve by the then minister for the arts after it was awarded an exceptional rating.

It was then rescued by the Norfolk Record Office in 2004, in partnership with the Norwich Town Close Estate Charity.

A successful bid in 2008 for funding from the National Cataloguing Grant Programme enabled a team of experts and volunteers to repackage and archive more than 2,650 documents connected to the company.

The exhibition, called Leading the Way: the Archive of G King and Son (Lead Glaziers), will run until Saturday, April 16 at the Norfolk Record Office, which is based in The Archive Centre on the County Hall site at Martineau Lane, Norwich.

Admission is free. For more information and opening hours, visit www.archives.norfolk.gov.uk, while anyone interested in seeing a more detailed catalogue can visit http://nrocat.norfolk.gov.uk.