west of Newton Abbot. In October 1958 D800 became the first locomotive to take up the class's new diagram of the up Cornish Riviera Express (Penzance to Paddington), the 18:30 Paddington–Bristol and the 21:05 Bristol–Plymouth – the last part of the diagram allowing the locomotive to return to the brand new depot at Laira in Plymouth once this was fully operational in 1961. The maximum speed of the D800 class was officially but this could not be rigidly enforced because the transmissions could not be precisely governed. was recorded by D801 in private tests during 1959, albeit on a downgrade. The summer of 1959 saw service trains diagrammed for D800s with the Paddington–Bristol "Bristolian" set a schedule of 100 minutes. The outward journey via Bath required an average speed of and the return journey via Badminton averaged at . For a very brief period the D800s achieved both the schedule and more with D804 exceeding three times on one early run from Bristol. This was soon ended when the Western Region's civil engineers imposed a blanket maximum speed on all the Region's main lines, where for five years there had, uniquely to BR at the time, been no restrictions at all. The root cause of this worry was the effect of small-diameter powered wheels carrying far more weight per inch of tread than those of a steam locomotive. These concerns arose particularly from experiences in the United States of America although the significant rail damage reported there was mostly caused by wheel sliding under braking with heavy trailing loads which were very unlikely to occur on BR. With the benefit of modern hindsight, it is possible to say that even though the full US experience would not be replicated, "gauge corner cracking" (the formation of microscopic cracks in the rails that was the primary cause of the Hatfield rail crash of 17 October 2000 in the UK) could have been a possibility if the schedules had been adhered to. Around this time, several D800 drivers began reporting uncomfortable lurching over points or on poorly maintained track at high speeds. The problem was eventually traced to the novel design of the bogies and their means of attachment to the locomotive bodyshell: it had given the German V200s no trouble because of the speed limit on the German Federal Railway at the time. High speed running magnified the effect of the almost