During the Second World War the Bank of England was concerned that the currency could be counterfeited. To thwart counterfeiters it was decided to change the colour of the £1 note from the traditional green to blue pink Perhaps the most significant change was the introduction of an embedded security thread in the body of the note. We regard this feature as standard today but then it was considered revolutionary. The bank ditched the new colours once the war was over reverting to the traditional green. The new security feature was retained .
This is a classic note which any Bank of England collection should include. It is important because it was the first note to contain an embedded metal security thread.