The figure compared to £43.4m in the same period of 2012.
Overall turnover for the Williams group of companies for the half year stood at £57.7m compared to £64.9m in 2012.
Williams, once the dominant team in Formula One with nine constructors’ titles and seven drivers’ crowns between 1980 and 1997, has scored just one point in 12 grands prix so far this season.
The team said the results of its investment businesses, Williams Hybrid Power and the Williams Technology Centre in Qatar were in line with a long-term business plan.
Full-year results were expected to show group turnover of £105m-£113m compared to £127m in 2012.