Worst blinding I ever received was travelling south through the Blisworth Tunnel, about 500 yards from the end. The trip boat that works out of Stoke Bruerne, taking tourists from the top lock to the tunnel and back, lit up the tunnel with the most stupidly powerful lamp just so his customers could take a look in a hole.
I was not impressed.
I have recently changed my tunnel lamp, due to a intermittent fault, with a small 6 LED lamp. I have yet to test it in a tunnel, but I will be facing the tunnel roof.