East Anglian Air Ambulance

A brand book gives you a palette and a few hero layouts. It does not tell you what the yellow does behind 14px body text, on a disabled button, or on a form error. Those states had to be resolved across donation, lottery and shop, to a fixed date. The brand yellow scores 1.56:1 on white and fails every threshold. This is a site whose navigation carries a text-resize control, so it had already declared who its readers are long before anyone opened a brand guideline. Yellow was restricted to display sizes with a darkened amber for small text. The brand agency read it as breaking their palette, and the argument that settled it was that they had never been asked about 14px. Shipped on schedule for a national campaign, with the resize control and contrast ratios intact through a full rebrand. No metrics, no client quote.