The archives at Chatsworth are full of fascinating documents, letters and journals extending over 500 years of the Devonshire family history.

In order to ensure these items are available for future generations of colleagues, academics, and visitors to view and learn from, we take on various conservation projects throughout the year to restore these items as best as possible.

In 2021 we received a grant from the National Manuscripts Conservation Trust and the Golden Bottle Trust to help conserve and create bespoke storage solutions for nine highly significant, early modern documents that reflect the political influence of the Devonshire family. 

Included within those selected were –

• Letters patent granting the Dukedom of Devonshire in 1694, with royal portrait and the Great Seal of William & Mary.

This document is of vital importance to Chatsworth as it recognises the role played by William Cavendish, 4th Earl of Devonshire, in the Glorious Revolution.

• The carefully-negotiated marriage settlement of the 2nd Duke of Devonshire whose wife, Rachel Russell, was daughter of Lord Russell, friend of the 1st Duke and executed for his role in the Rye House Plot.

This document had not been uncatalogued previously and has not been studied in any detail; by conserving it we are able to get a clearer picture of the 2nd Duke of Devonshire’s life.

• A 4.5-metre illuminated pedigree drawn up in 1626 for Richard Boyle, 1st Earl of Cork – Lord Treasurer of Ireland and a key figure in the Elizabethan colonisation of the country.  

Never previously used by researchers, this has been hailed as a major find by Dr David Edwards of University College Cork – leading Boyle historian. Richard Boyle was the great-great-grandfather of Lady Charlotte Boyle (1731-1754), wife of William Cavendish (1720-1764), who later became the 4th Duke of Devonshire. 

As the work on these documents required expert care we employed the help of Antony Oliver, conservator at Sheffield City Archives.

Conserving the historic documents

Before any treatments were undertaken a full assessment of each document was carried out. This included recording each item’s current physical condition; this is a vital part of the conservation process as the conservator needed to make informed decisions on the type of treatment(s) and materials required to prevent any further damage and on how best to preserve each item’s longevity.

Inks and pigments were assessed for their overall stability and once this had been established each document’s surface was cleaned with a smoke sponge.

The sponge absorbs and removes layers of dirt on the surface of the document; after this, soft-haired brushes gently removed any crumbs and debris.

The next stage in the process may sound a bit strange; however, it was a necessary procedure – once the assessment and cleaning were complete each document was placed inside a damp pack which introduces moisture in a controlled way.

Some of the items sent for conservation were written on vellum - a prepared animal skin or membrane; the use of vellum as a writing surface has been an accepted practice for many centuries. Over time vellum reacts to changes in environmental conditions, it can sometimes shrink in a dry environment; this can occur during winter in heated buildings. By introducing moisture the document is able to relax and become flexible; however, too much moisture can distort the material.

The document is then dried immediately between sheets of multi sorb, boards and weights which enables the team to re-role the documents and stop them from cracking. This is a delicate and skilled process as too much weight or pressure can cause further damage.

Conserving the historic seals

Amongst the items sent to the conservator were a variety of seals: seals were and still are used to authenticate or validate certain types of document. One of the seals that was sent for conservation was the Great Seal of William and Mary, which was attached to the document granting William Cavendish the Dukedom for the part he played in the Glorious Revolution.

From the inspection carried out, it was found that the pendant seal was attached to the document with cord which was originally gold in colour. The seal was still in its original metal skippet and appeared to be intact and undamaged. Initial inspections noted some historic repairs to the seal where it may have fragmented and come loose from the main portion.

The first steps in the process of conserving the seals were to clean them with a mild detergent to remove surface dirt and debris. Then each of the damaged seals were repaired with beeswax and resin, loose or detached fragments were reunited with the seal by running molten beeswax along cracks for consolidation and support.

In one rather extreme case, the only way of safely removing the seal from the metal skippet whilst ensuring it remained attached to the document was to saw into the base of the skippet using a junior hacksaw. This facilitated the careful cleaning of the seal, and the skippet has also been retained.

Future preservation

Each document and seal had a bespoke preservation packaging system designed in order for them to be handled safely when required for consultation or display purposes.

For example, the marriage settlement of the 2^nd Duke of Devonshire to Rachel Russell now has been placed in a tailor-made archival box with a removable lid using premium archival folding boxboard.

The base of the box is covered in a protective sheet of plastazote (a type of foam) covered with Tyvek fabric - high-density polyethylene fibres which are able to withstand folding and flexing without tearing.

A separate removable protective sheet is then placed on top of the document for further protection whilst in storage.

Putting it into practice

As part of the project, Anthony Oliver from the Sheffield Archives delivered a training workshop to the archive and preventative conservation teams as well as some of the archive volunteers at Chatsworth.

During the event, Anthony demonstrated how the work was undertaken on the project documents and provided a practical workshop on the best methods for cleaning and packaging vellum and parchment documents with seals.

This workshop was gratefully received by the team and volunteers who have already started to put these skills into practice. Two of our volunteers are working on a large collection containing thousands of parchment documents; they are carefully cleaning each document and creating bespoke bags to house their seals.

The preventative conservation team have carried these skills over to the ongoing map condition survey and documentation project which started last year.

Within the archives there are over 1,500 historic maps and ensuring they are cared for properly for future generations is of great importance. The team have been condition checking, cleaning, updating our internal catalogue and repackaging each map to ensure they will still be around in years to come.

The funding we received from the National Manuscripts Conservation Trust and the Golden Bottle Trust has been vital in enabling the charity to carry out this programme of conservation work on these historic documents.

Without this funding, we may not have been able to preserve these documents and make them available to researchers or use them in displays and events.

Our registered charity, the Chatsworth House Trust, is dedicated to looking after the house, collections, garden, parkland and woodlands for the benefit of everyone.

All income from ticket sales, gift aid, our Chatsworth Friends and Patrons programmes, partners, sponsors and funders goes directly to the charity and is reinvested in the upkeep, preservation and improvement of Chatsworth, our learning programme and essential conservation work, such as the restoration of historically significant documents such as these.

Find out more about the Chatsworth House Trust and how you can get involved using the links below.