LONDON, Jan 16 (Reuters) - British housebuilder Barratt said it expects a "significant" improvement in profitsfor the full year 2012-2013 after its profit before tax morethan doubled in the first six months to December. Barratt, the UK's largest housebuilder by market volume,said on Wednesday it expects pre-tax profit over the half yearperiod to rise by 108 percent to 45 million pounds ($72million)and posted group revenues of 950 million pounds, in linewith the prior year. The company completed 5,085 units over the period and secured private forward sales, excluding joint ventures, of536.5 million pounds by the end of December, up 35.5 percentover the prior year, it said. "This has been a good first half performance," Group ChiefExecutive Mark Clare said. "In addition, we have been investingfor the future, successfully securing higher margin land both inthe South-East and across the rest of the country that willdrive further profit growth. "We are on track to deliver around half of our full yearcompletions from higher margin land, and combined with ourcontinued focus on driving efficiency across the group, weexpect to deliver a significant improvement in profitability forthe full year 2013." Barratt said it had agreed terms on 453 million pounds worthof new land in the first half, equating to 9,320 plots on 67sites, and that it expects to agree terms on 15,000 plots forthe full year. It also said that it had bought two sites in London with adevelopment value of 400 million pounds which would provide morethan 1,000 new homes for the capital. Barratt and its rivals such as Taylor Wimpey andPersimmon have in the past year sought to beat asluggish market by buying land cheaply during the recession,building more lucrative family homes rather than flats andfocusing on areas where prices have stayed strong such as Londonand south England. Shares in Barratt, which have more than doubled in priceover the past year, closed at 226.5 pence on Tuesday, valuingthe company at 2.2 billion pounds.