By Elliot Gulliver-Needham Bank of England banknote printer De La Rue has agreed to sell an arm of its business to an American firm for £300m. The London-listed company announced this morning that it had entered into a definitive agreement for the sale of the group’s authentication arm to Crane NXT, a New York-listed industrial technology company. When the sale is complete, De La Rue will be solely a currency printer, ditching its authentication business that works with government clients to help detect fraud. The sale comes following a series of problems for the company, most recently being f…