This created a bottleneck at Finsbury Park, back then the northern terminus of the Piccadilly line. By 1923, a public campaign against the 1902 parliamentary ban emerged, and Frank Pick had risen to assistant managing director of the Underground group. To help address this issue, Frank Pick gathered photographs of the congestion at Finsbury Park and distributed to the press. In 1925, the LNER gave in to the objection. Pick began working on the extension proposal and obtained parliamentary approval in 1929. The alignment was based on the absence of property development along the line. Funding was obtained from legislation under the Development (Loan Guarantees and Grants) Act instead of the Trade Facilities Act. Tunnel rings, cabling and concrete was produced in Northern England, while unemployed industrial workers there helped in the construction of the extension. 22 tunnelling shields were used during construction which started in 1930. The station was opened on 19 September 1932 as the terminus on the first section of the Piccadilly line extension to Cockfosters. The line was further extended to Oakwood on 13 March 1933. Its name was chosen after public deliberation: alternatives were "Arnos Park", "Bowes Road" and "Southgate". Incidents On the night of 13 October 1940, during the Blitz, a lone German aircraft dropped a single bomb on houses to the north of Bounds Green station. The destruction of the houses caused the north end of the westbound platform tunnel to collapse. As a result, train services between Wood Green and Cockfosters were disrupted for two months. On 11 August 1948, a passenger train was derailed when the front and rear bogies of a carriage took different routes at a set of points at the station. On 7 July 2005, a bomb exploded on a train travelling between King's Cross St. Pancras and Russell Square. Train services between Hyde Park Corner and Arnos Grove were disrupted until 4 August of the same year. Station building Like the other stations Charles Holden designed for the extension, Arnos Grove was built in a modern European style using brick, glass and reinforced concrete and basic geometric shapes. A circular drum-like ticket hall of brick and glass panels rises from a low single-storey structure and is capped by a flat concrete slab roof. The design was said to be inspired by the Stockholm City Library and Swedish architect Gunnar Asplund,, although Charles Hutton, Holden's chief assistant stated