Unfortunately we got there too late to see them actually hitting or shooting one another (we got there at two, and the armed displays had all finished by one, which seemed odd timings for a Sunday). However we did see a Mummers Play, watch a knight get kitted out for battle and then the children got to do some Bill Drill. We made our escape before the dancing (needing adult volunteers) re-enactment started!
All this was free as I'm an English Heritage member and can take any number of kids in with me. I certainly get great value (and pleanty of wargaming inspiration) out of my annual £47 fee.
The castle itself is C12th and was slighted after the Civil War as it had been a royalist thorn in Cromwells side. It is also one of the locations in Walter Scott's Ivanhoe novel.
It was a lovely day, so I took a couple of pictures.