I remember camping in the park near the stadium in Cardiff 30+ years ago. We caught Elvers (baby eels) in the nearby river but the best bit is that it rained and the whole site turned into a quagmire and us kids helped push the cars through the mud. After sitting through the endless tedium of the convention slipping and sliding about all over the place and getting absolutely covered in mud was absolute heaven!
I also remember making sandwiches with my brother at Dudley assembly hall and getting into trouble because we wrote things like "Comrade Mattski" and "Captain Sam" on our paper hats, which looked vaguely military to us. We only got that "privilege" once.