Separation standards are minima. I am pleased to see that nats has finally woken up to this LCY problem. The stepped SIDs from the LCY westerly runway were always fraught with level-bust risk. Leave aircraft on the SID and there would be occasional high ROC level busts especially by high performance biz-jets. In the past inexperienced nats investigators and inexperienced nats managers with little knowledge of the operation expected the Thames controllers to intervene during a 'bust' as a safety net. Fail dangerous. One only has to read some of the pathetic un-enlightened incident reports. Some Thames controllers were fed up with these busts and stopped each departure at a simple and straightforward 3000ft in an unsupported effort to prevent them. Pilots, however, sometimes climbed to 4 at the 3 to 4 point regardless believing the stop to be a SID step reminder rather than a maximum level. These are dangerous nats SIDs about which very little has been done about over two decades. An accident waiting to happen and has always been thus since '87. Outrageous.