 Later they were transferred to the Northern line, but in 1995 they were replaced as non-standard by 1962 Stock cascaded from the Central line.The introduction of the 1938 Stock released considerable numbers of Standard Stock trains, which were scheduled to make up the shortfall on the Central line resulting from the extensions to the line.However, this process was interrupted by the Second World War, and although much of the Standard Stock had been through Acton Works for refurbishment, it was stored, as the opening of the extensions was delayed.