Holiday time in Open Space this week. The drivers and clippies of Putney Bus Garage step off their buses on to the somewhat faster route of the world's largest corkscrew rollercoaster. That's just one of the terrors and delights they try with their families during a day out at Britain's largest pleasure park, Alton Towers In Staffordshire. But no day out is complete without an argument or three on the long journey home. The kids slept right through it.