Given the commitment (and funding) by the British government to promote physical activity among all ages, and despite the inevitable political manipulation of physical education (PE) and school sport, there is now an ideal opportunity to focus on primary schools as a key target group for the future. This study determined the physical activity levels of a sample of pre-adolescents over time in a primary school setting. 374 children (5-11 yrs) were directly observed for a total of 30,650 minutes. Continuous observations of 374 primary PE lessons, 374 break times and 215 lunch times were undertaken between 1999 and 2004. The actual intensity and type of activities taking place were also recorded in five-minute blocks of time. The children were engaged in activity of at least moderate intensity for 11.8 percent of the total time observed, being more active in PE lessons and break times than in lunch times. Boys were shown to be more active than girls, recording activity of at least moderate intensity for 13 percent of total time compared to 10 percent for girls. Given the available data, the primary school is not delivering on its potential to be a good setting to promote physical activity. (Contains 5 tables and 2 figures.)