During the Second World War, the Bank of England felt the need to protect its currency from counterfeiters. It decided to change the colours of the £1 and 10 shilling notes for the duration of the war and add a revolutionary (at the time) inner metal security thread. The £1 changed from Green to Blue Pink and the 10 shillings from Red Brown to Mauve. The basic design was unchanged from the pre-1940 10 Shilling note. Printed by offset-litho at St Lukes's Works'sOld Street London and Overton Hampshire. The paper was manufactured by Portals Ltd. Legal tender until October 1962