The deal was signed late last week for a six figure sum which will see Primus take on a series of school and local authority contracts.
Primus was set up by a number of former Multiplex directors three years ago and is headed by Martin Tidd who was Multiplex UK managing director when the firm was building Wembley Stadium.
Primus is based in the City of London and will be taking over Rok’s Heathrow office as part of the deal.