The original charter was written in 1984. Although Nimbus was in its infancy all the criteria laid down then are still relevant now. This updated version directs and reflects the way in which work and business are approached. The word 'Nimbus' should be taken to include all the conservators, masons, administrative staff, directors and other employees who are referred to as 'members'.

• Nimbus will promote the highest standards of workmanship and craftsmanship based on sound technical knowledge.
• Nimbus will promote the dissemination of knowledge to and from its members.
• Nimbus will promote the use of traditional materials, whilst not excluding the use of proven modern methods and materials.
• Nimbus will encourage involvement of all members in the arts and sciences in order to widen their skills and imagination.
• Nimbus will promote co-operation between its members.
• Nimbus will promote a collective moral and ethical responsibility for and from each of its members.
• Nimbus will at all times ensure fair business practice.
• Nimbus will promote contributions in the way of letters, speakers and visits to other professional bodies.
• Nimbus will provide a written and photographic archive of the work carried out by all its members.
• Members of Nimbus will keep a minimum standard report sheet and a continuous diary recording all aspects of their work.