Schools programmes on ITV were generally between ten and twenty minutes in length. Unlike peak-time programmes (which were usually scheduled at times rounded up to the nearest five minutes), schools programmes were scheduled at very precise times, such as 10:03 or 11:32. Some individual regions, such as HTV Wales, sometimes showed their own programming instead of the network offerings, but would rejoin the network in time for the next scheduled programme, and so it was necessary to devise a flexible presentation system which would allow the network to effectively fill the time between programmes without resorting to showing a blank screen. Network schools presentation was provided by ATV and later, Central Independent Television in Birmingham with live announcements made by ATV & Central's staff announcers including Mike Prince, Stewart White, Peter Davies and Su Evans.