opened a line from Wembley Park to Stanmore, and the Piccadilly line was to extend north from Finsbury Park to Cockfosters and west from Hammersmith and took over the District line Harrow and Hounslow branches. Several stations were rebuilt in a Modernist style influenced or designed by Charles Holden, who called them his 'brick boxes with concrete lids'. Piccadilly line trains took over the District service to South Harrow in 1932, reaching Uxbridge the following year. Piccadilly trains reached Cockfosters and Hounslow West in 1933, although District line services to Hounslow continued until 1964. London Passenger Transport Board (1933–1947) In 1933, Harry Beck's diagrammatic tube map appeared for the first time. On 1 July 1933, the London Passenger Transport Board (LPTB), was created as a public corporation and the Metropolitan, the UERL underground railways, tramway companies and bus operators were merged into one organisation. On the former Metropolitan Railway the Brill Branch closed in 1935, followed by the line from to Verney Junction in 1936. It was proposed to electrify to Amersham with additional tracks from Harrow to Rickmansworth and to extend the Bakerloo line to Stanmore to relieve the bottleneck on the Metropolitan from Baker Street to Finchley. Before any work was started on the Met, the 1935–1940 New Works Programme was announced. This included extending the Central line to Stratford and then onto Epping and Ongar and the Northern line was to be extended north to High Barnet, Alexandra Palace and Bushey Heath and link up with the isolated Great Northern & City Railway, renamed the Northern City Line, which was to be extended beyond Finsbury Park to link up at Highgate. New trains were delivered before the outbreak of World War II in 1939, including 573 cars for the District and Metropolitan lines and 1,121 new cars (1938 Stock) for the tube lines. Following the outbreak of war, services on the Northern line between Strand (now Charing Cross) and Kennington were suspended as the tunnels under the Thames were blocked as a defence against flooding. The Metropolitan Pullman cars were placed into store and first class was removed from London Underground services. The New Works Programme continued, albeit at a reduced pace, the Bakerloo line taking over the Stanmore branch from the Metropolitan in November 1939. The Northern line reached Mill Hill East in May 1941, but by then work on the other Northern and Central line