Works were completed from Highgate to High Barnet and Mill Hill East and that section was incorporated into the Northern line between 1939 and 1941.

Further works on the section between Finsbury Park, Highgate and Alexandra Palace were postponed and the line continued under the operation of the LNER.

Because of wartime economies services were reduced to rush hours only, so that after the war the dwindling passenger numbers and a shortage of funds led to the cancellation of the unfinished works in 1950.

[2] With dwindling passenger numbers the station was closed by British Railways after the last train on 3 July 1954 along with the rest of the line between Finsbury Park and Alexandra Palace.

The line continued to be used for goods into the 1960s and by London Underground for train stock movements until September 1970 and was completely closed on 5 October 1970.