“Shall we stack the naked acres with our CPIs”

March and April are the CPI months. The National Trust is a unique British organisation set up in 1895 to conserve places of historic interest and natural beauty. How do you do that? How can NT measure how successful it is? Where should it spend its limited resources? Is a Joshua Reynolds painting in a mansion more important than an orchid on the ramparts of an Iron Age hillfort? The answer is… the Conservation Performance Indicator (CPI).

Picture a room with a table, a powerpoint projector and a circle of chairs: perhaps a cafe on the Somerset coast or a barn in Dorset or even an old engine shed in Somerset. The players take their seats. The ecologist, the curator, the building surveyor, conservator, gardener, ranger, manager and…archaeologist. The main conservation features of the property are agreed and then three lists are made and the match begins. Which is most significant, which would have the greatest conservation impact if lost and which requires resources most urgently. For some places the top points are easier to allocate than others. Stonehenge landscape has archaeology at the top but what of the Stourhead Estate in Wiltshire.

Stourhead Lake and Pantheon aquatic archaeologists from NAS prepare to dive

Is the famous 18th century landscape garden with its grade I listed temples, lakes and bridges more important than the incredibly rare Pope’s cabinet in the house or does the scheduled Early Neolithic causewayed enclosure on Whitesheet Hill rank higher than the SSSI chalk downland sward that covers it ? (well, they tend to be mutually beneficial so taking care of the ecology generally benefits the archaeology).

Whitesheet Hill, Stourhead. A Bronze Age burial mound (c.2000 BC) above a causewayed enclosure (c.3600 BC)

Then ideal conservation objectives are set for each feature and actions are agreed which after 12 months will be scored depending on how much has been achieved. This is a good time to meet conservation colleagues and work together on integrated conservation management. This week the CPI scores for Kingston Lacy (Dorset), Stourhead (Wiltshire), Tyntesfield (Somerset) and Purbeck (Dorset) have been decided.