I installed a new sound system in the hall and added a couple of old Celestion Dittons that I had in my loft. Then I sat and watched and listened to the ugh Christmas play with the parents - just in case of technical difficulties. About 5:30, I thought I'd give the whole set up a thorough try out with some Black Sabbath and see how it went. Wow, but how was I to know there was a Governors' meeting going on down the corridor. Doh ! At least I wasn't playing air guitar.