Acquisition by Carillion is hailed by chief executive John McDonough as a major milestone.
In a statement this morning, John McDonough, Carillion chief executive, said: "The acquisition of Mowlem is a major milestone for Carillion and a step change in our development.
"In Mowlem we are gaining a business with a proud heritage as well as one with excellent complementary skills and market strengths to our own.
"Combining these will create a support services and construction company that I am confident will rank with the very best in the UK, in terms of both size and capability. We also have a strong and growing presence in good international markets."