In 1605, a man named Guy Fawkes was part of a plot to blow up the houses of parliament and the king. However, the plot was discovered and Guy Fawkes was captured and executed.
This event is commemorated every year with traditional fireworks and the lighting of a bonfire with a 'guy' on top. Here's a website with more infomation:
http://www.woodlands-junior.kent.sch.uk/customs/Guy.html
Here's the traditional lighting of fireworks

Unfortunately, our bonfire didn't have a 'Guy' on top but instead had a model which looked strangely like the houses of parliament. Not quite in keeping with the usual tradition then.