Demand for flat-screen televisions has more than doubled in the past year as consumers' viewing habits change dramatically, putting the remaining UK-based manufacturers of conventional TVs under severe pressure. According to data from GfK, a market research organisation, to year end- November, retail sales of flat-screen systems reached 1.82m units, up from 720,000 in the previous 12 months.Over the same period, flat-screen TVs accounted for 63% of the total £2.57bn retail value of all TVs bought in the UK, compared with just 37% the previous year. The sudden surge in popularity of flat-screen TVs - mainly comprising sets based on liquid crystal & plasma displays - explains the decision this week by the DSG International retailer to stop selling conventional cathode-ray tube TVs in its Dixons high-street stores. The enthusiasm is due largely to price reduction.