LSL Property Services, the owners of the Marsh and Parsons chain of estate agents, has dropped sharply after revealing a pre-tax loss for the first six months of the year.In the six months to the end of June the firm took a loss of £7.9m compared to a profit of £6.5m in 2011.The loss came despite a 17% rise in revenues to £120.8m and an increase in operating margin from 11.5% to 12%.The problem for the group has been a large provision for personal indemnity (PI) claims relating to the property boom between 2004 and 2008 and the loss of a surveying contract with mortgage provider Cheltenham and Gloucester. PI provisions have risen to £17.3m due to a "recent deterioration" in claims. The loss of the C&G contract saw income in the surveying business decrease 10% to £34.4m.The group's shares had fallen 12% bt 10:54.