Page 133. " Her great horsy face had turned the colour of molten lava "

Lava comes from volcanoes when they erupt. The Trunchbull's face might have looked something like this...

 

Page 137. " with the same kind of care the Duke of Wellington had done before the Battle of Waterloo "

The Battle of Waterloo against Napoleon Bonaparte and the French Empire took place on Sunday 18 June 1815. The Allied forces were led by the Duke of Wellington. Their victory ended Napoleon's reign of the French Empire (and probably took quite a bit of careful planning).

 

 

Page 137. " a colony of newts "

A newt
Creative Commons Attribution Share AlikeA newt - Credit: Lmbuga
Roald Dahl gives us a good description of what a newt is, but here's a photo to help you get the picture...

Page 142. " You can hear the same sort of thing if you walk through a riding-stable when the horses are being fed "