Persimmon’s legal completions dropped by a third, with turnover plummeting 40%, the volume housebuilder has stated as part of its trading update for the year ended 31 December 2008. Legal completions totalled 10,202 units at an average selling price of £172,000, compared to 15,802 units at an average selling price of £190,000 for the year ending 31 December 2007. The …