Stress-testing oldies from California

As this ongoing forum discussion proves, there is a great deal of interest in how wines age, and what constitutes an improvement in quality as wine matures. Inevitably, different personal tastes mean there can never be full consensus, but surely there are certain factors that we can agree are an essential part of what makes older wine appealing. I considered what these might be before attending a tasting intended to 'demonstrate the age-worthiness of California's greatest wines'.

Firstly, structural balance is important. That...