The Blackwell business originated in 1946 with its founder Chris Blackwell, carrying out local agricultural contracts and gradually moving onto a variety of larger contracts in different parts of the country.

In 1956 the company was officially registered and the first major contract was the M1 motorway commencing in 1958 for John Laing Construction on 'C' Section, a 12.3 mile stretch from Gayhurst to Kislingbury in Northamptonshire. A second scheme for Laing soon followed, on the M2 in Kent.