The firm will create new studios and an extra 35,000 sq ft of new and refurbished office space, designed by London architects Jacobs Webber.
The exterior of the building is to be fitted with colourful briese soleil solar shading, plus a green wall, which was created with specialist input from Kew Gardens.
The canal-side complex is regarded as one of Britain’s finest examples of post-modern architecture.
It was designed by architect Sir Terry Farrell who, in 1981, oversaw the conversion of a 93,418 sq ft garage into the headquarters of TV-am, Britain’s first commercial breakfast TV station.
Peter Jacobs, construction managing director of Morgan Sindall, said: “We welcome the opportunity to use our skills and capabilities at one of the best known buildings in North London.”
Kerry Waterman, Vice President, Planning and Design at client VIMN UK, said: “This is an exciting and challenging project, working around an operational site, but the final result will provide an exceptional and creative working environment.”
A remodelled atrium with enhanced use of glazing and skylights will complete the new look building.
The project is due to be finished by December 2012.