One-off charges lowered first half profits at banknote printer and cash handling machines specialist De La Rue, but currency translation benefits and good banknote demand meant a strong underlying performance.Revenue for the six months to September rose by 3.1% to £252.2m, with underlying operating profits up by 17% to £51.0m (2008/2009: £43.5m). The movement in the value of sterling against the US Dollar and euro added £14m to revenue and £4m to operating profit.Profit before tax, though, decreased 6.4% to £44.2m (2008/2009: £47.2m) after costs of reorganising the cash processing division."The board remains confident in the outlook for the full year. Looking forward at this stage into the new financial year, banknote volumes should remain at similar levels but the unusually strong margin mix in currency may not be repeated. It is expected that this will be offset by productivity gains, cost reduction and improved trading in other parts of the business," De la Rue said.The interim dividend rises by 3% to 14.1p.