Eighteen hours so far. My GiffGaff coverage was zero all yesterday afternoon and evening, and is intermittent now.
These things happen I suppose, but when you're stuck in a hospital with no way for your lift home to contact you, and only uber-expensive payphones to contact them with it becomes less funny. At first I was worried the X-ray department had fried my phone, as it was working fine just before the x-ray, but I had No Network on leaving X-ray.