I don't think we've ever really been in the forefront of nuclear power. Calder Hall was claimed as the first commercial station, but it was in fact a production reactor for out cold war bomb production. The small amount of generation for the grid was a convenient cover story to attempt to hide it's true purpose.
The Magnox and AGR reactors that followed use essentially the same technology as the Russian RBMK, like the one at Chernobyl, graphite cored moderation which is not inherently fail-safe, quite the opposite. All these of this type are very efficient, but given the risk factors the inherently much safer PWR is the world's favourite and the majority of all power station reactors.
We built one of these, Sizewell B, but took 14 years (!) to do it at great cost. If we'd swallowed our pride and used an established US design we could have built in just 4 years easily at much lower cost. The South Koreans build these in just two years and have an excellent nuclear safety record. We should be replacing our stock and adding to it with the latest Westinghouse PWR reactor design, inherently very safe and with every known protection. These will even take care of a Fukushima type of incident, and a tsunami is very unlikely to occur in this region!