The station was busy and unsuccessful attempts to control crowds with gates at platform level were made in 1918. In the 1930s, the station was included amongst those modernised in conjunction with the northern and western extensions of the Piccadilly line. A new sub-surface ticket hall was opened on 18 September 1933 with a pair of Otis escalators provided to replace the lifts. The new ticket hall was accessed from subway entrances in Piccadilly. On the north side, an entrance was provided in Devonshire House on the corner with Stratton Street; on the south side an entrance was constructed on a piece of land taken from the park. The shelter for the southern entrance was designed by Charles Holden. The original station building, the lifts and the redundant below-ground passages were closed and the station was renamed "Green Park". Part of the ground floor was used as a tea shop until the 1960s. In 1955, a third escalator was added to help deal with increased passenger numbers.