A tower block falls on Waterloo station, eight tube carriages are crushed and large-scale emergency service procedures are activated. Gavin Haynes reports from the largest emergency exercise training event ever held in London.The event – which cost £750,000, roped in 70 emergency organisations, 2,000 volunteers and even featured a fake morgue, hospital and tube station – was all orchestrated to prepare the British services and international teams for disaster.Is this a glorified drama school exercise or Britain at its best preparing for the worst case scenario?