Peter Kerslake says "At this time 18000 was rostered on Paddington to Plymouth express passenger workings which took it down on Mondays and Wednesdays, the locomotive returning from Plymouth, usually on either the 7.15 a.m or, more often , the 8.30.a.m. departure on the Tuesdays and Thursdays following an overnight stay at Laira. Fridays and Saturdays were Bristol line duties and Sundays were set aside for maintenance at Old Oak .I think that this view is of 18000 on a Plymouth duty as most of the West of England departures at Paddington were from Platform 1 as shown here. This period of workings began on 28th August 1950 and continued until the end of September, with a series of tests being undertaken in mid September on the Plymouth runs to see how 18000 compared with a King and Castle on these rosters, with the gas turbine putting in some impressive performances."