The Oak at Ragley Hall: A Modern-Day Inspection

Written by Phil Johnson of Professor Shearbomb Ltd

When John Trenchard of Arbor Venture Ltd asked if I’d inspect the lovely English oak tree at Ragley Hall Estate, I jumped at the chance. This stately oak, a modest 17 metres, stands alone in a field for most of the year but becomes the centrepiece for 20,000 visitors at the APF Show.

John was pretty sure the tree was fine, but a significant bark wound running from the base of the trunk to the primary junction warranted a closer look. With its role in the tree climbing competition at stake, John wanted peace of mind. So, armed with the PiCUS 3 Sonic Tomography System, I set out to gather more information and ensure the tree’s suitability for climbers and spectators alike.

I know some seasoned arboriculturists might say, "I can tell you exactly how decayed that tree is with my nylon mallet," but I’m all about bringing arboriculture into the modern era. Using equipment like the PiCUS 3 as part of my internal tree inspection allows me to present findings in a way that’s easy for everyone to understand.

On a sunny June morning, with stinging nettles tickling my earlobes, I established a working platform around the trunk and carried out a full Visual Tree Assessment (VTA). I set up the PiCUS tomograph and planned to produce three tomograms to assess the internal condition along the bark wound. During the VTA I noticed some lovely adaptive growth at the base, possibly a natural response to the hollowing typical of oaks this size and age.

After considering the tomograms in relation to the tree’s species, life stage, location, and planned use, I concluded the tree was fit for its role at the APF Show.

For added thoroughness, I conducted a VALID Tree Risk-Benefit Assessment using the inspection data. Despite its basic level, the risk assessment, combined with our advanced inspection, rated the risk as ‘Acceptable’ given the event’s likelihood of occupancy. Just for kicks, I also produced a TreeCalc Evaluation to get a Safety Factor, considering the tree’s species, height, trunk diameter and hollowness, crown spread, and terrain.

All this information will be displayed around the tree’s fencing during the APF, so do come by for a chat. I’d love to share my findings and maybe even some tales from the field. After all, there’s always more to a tree than meets the eye!