D H F Somerset was Chief Cashier at the Bank of England between 1980 and 1988. During that period, there were 4 distinct varieties of the Florence Nightingale £10 note. Three had a hidden security thread and 1 had a stardust silver thread. The last of the £10 notes with the buried security thread have the catalogue reference B348 in Vincent Duggleby's English Paper Money. These were also the first £10 note to be printed on giant web presses with the fronts printed in intaglio and the backs with offset lithography. The Bank included a little L on the back to distinguish this variety from others.