Philip Wilbourn has been appointed as an expert witness on a number of occasions on matters that have both gone to court such as Blue Circle Industries Plc v Ministry of Defence [1998] EWCA Civ 945 and others that have settled at mediation or have settled out of court. Such work requires a broad knowledge of environmental issues and the market place. Every case is completely different. He has achieved as much as 54% diminution in value in one case. Wilbourn & Co work within the RICS Guidance Note Surveyors Acting as Expert Witness 4^th Edition.