German electronics and engineering powerhouse Siemens is to sell its electronic warfare firm, Roke Manor Research, to decoy countermeasures specialist Chemring.Chemring is paying £55m to acquire Roke, an engineering company that provides contract research, product development and low volume production for a wide range of UK and international customers. Defence and homeland security represent 75% of Roke's existing revenues. The company has 450 employees, including over 300 highly qualified engineers.In the year to 30 September 2009 Roke's revenue was £45.3m, while in the eight months since the end of September it racked up sales of £28m, compared to revenue of £26.9m in the corresponding period of the previous year,Underlying operating profit before non-recurring costs in the year to 30 September was £3.5m, while underlying pre-tax profit, including research and development tax credits, was £4.9m.Roke's gross assets at the end of September 2009 were valued at £40.7m.The order book at the end of May 2010 was worth £37.2m, £0.8m lower than it was in May 2009."The acquisition of Roke will substantially enhance our existing technologies in a number of our key market sectors and will provide a growing number of products and technologies that will allow the group to enter adjacent attractive, high growth markets," said David Price, chief executive of Chemring.