In the early 1960s there was a plan to re-equip the Piccadilly line with new trains and transfer its newer Standard Stock to the Central line to replace the older cars there, some of which had been stored in the open during the Second World War and were becoming increasingly unreliable.
I begyndelsen af 1960'erne var der en plan om at udstyre Piccadilly line med nye tog og overføre dennes nyere Standard-materiel til Central line for at erstatte de ældre vogne der, hvoraf nogle havde været opbevaret udendørs under 2. verdenskrig og var blevet mere og mere upålideligt.