Grange specialises in the technology sector with clients including NEC, Minolta, Panasonic and Xerox. It is one of the top five UK business-to-business agencies with billings of £11 million.
The purchase of Grange follows Interfocus' acquisition of Osprey last year. Interfocus bought itself out of the Lowe Group before snapping up Osprey and then selling to Canadian company Maxxcom.
Interfocus has also strengthened its senior management team with the hiring of Matt Atkinson as chief executive. Atkinson was previously managing partner at Omnicom's direct marketing agency Tequila. He replaces Chris Still, who joined Interfocus as part of the Osprey management team but left the agency earlier this year.
Grange will be renamed Interfocus Technology and will relocate its UK office to Interfocus' London headquarters. It also has a US office in Los Angeles.
Interfocus is taking a 76 per cent stake in Grange, with its management retaining 24 per cent. Chris Zandonati, managing director at Grange, will take the same role at Interfocus Technology.
Matthew Hooper, chairman and chief executive at Interfocus, said: "As an agency we have always pursued the multi-discipline ethos. With the birth of Interfocus Technology we have found a partner who shares our views on marketing requirements and brings integrated marketing skills to a specialist sector."