Just for interest. We were away in Ireland for a week in May and travelled West out of Dublin taking the Toll roads. The return was just the reverse. We thought we had paid all the Tolls, be it kiosk or online. But just received a letter saying we hadn't paid on one section of the M50. Checking back, they were correct. Oops. But the a addition charge for non-payment was pretty much the same as the Toll charge. Very fair in my eyes. I bet the Thames Crossing isn't that generous.