The object of our investigation was the mechanism underlying spontaneous activity of the sinoatrial node (SAN), the pacemaker region of the heart, where cells contract spontaneously at a regular rate. I was indeed quite excited. The current we were recording was really strange: inward and activated on hyperpolarization, a very unusual, previously unknown property (figure 1). It was late 1978, and I had been a postdoc visitor in Denis Noble’s laboratory in Oxford for almost two years. I was working with Hilary Brown and Denis Noble’s wife, Susan (Brown et al., 1979).