Late birthday wishes too....
I suffered from warped discs with my last Morgan - a new 3.7 Roadster. They had to be replaced under warranty. I've owned enough cars to know about cold water and hot discs - it wasn't this. Nor was it caused by driving like a loon. To be honest I have no idea what caused it, but it happened all the same.
It was definitely the discs - lift the wheel, rotate and you can feel the catch on the pads.
