UK food manufacturer Northern Foods has posted a drop in annual pre-tax profits in line with expectations and warned that tough conditions at its biscuit unit would impact its first-half grocery performance. The group, which makes own-label ready meals and desserts for UK food retailers such as Marks & Spencer, reported pre-tax profits before goodwill amortisation and exceptional items of £97.5m (US$159.7m) for the year to end-March, a drop of 3.5% year-on-year.