That's interesting, Flatiron, there are several different explanations of the Vulcan Heathrow tragedy in "The Vulcan Story" by Tim Laming, that I am reading at the moment.
The most plausible to me (an ex PAR technician) is that there was divergent osillation due to the time lag between the GCA controller and the pilot. The controller had not handled a fast jet before and the Vulcan pilot had not used civilian GCA before. According to Peter Rivers, who wrote the chapter, "the delay in the pilot's response to the controller's instructions, and the delay in the controller following the radar plot, led to the flight path swinging further and further above and below the correct one, until the final low point caused the u/c to hit the ground, pushing it through the wing's flying controls."