Webb's compound locomotives were generally considered a failure and Whale commenced the programme of converting some of these to simple-expansion locomotives, and replacing others. In 1904 he introduced the 4-4-0 "Precursor" class, an entirely new design which was in production within nine months of Whale's appointment; by June 1906, there were 110 in service. The "Precursors" were able to keep time when handling greater loads than their predecessors. They were followed by the 4-6-0 "Experiment" class, and these two formed the basis for several subsequent LNWR locomotive classes.