Complex sentence: Maunsell had also applied snifting valves to the class, but these were removed by his successor Oliver Bulleid, who also fitted U1 class chimneys to improve the draughting of the class.
Split into simpler sentences: Maunsell had also applied snifting valves to the class, but these were removed by his successor Oliver Bulleid. Bulleid also fitted U1 class locomotive chimneys to improve the draughting of the class.