The company was founded as a private partnership between Basil Mott and David Hay on 30 July 1902. Prior to forming the partnership both had spent time building London tube railways and Hay had worked on the Blackwall Tunnel, so it was no surprise that they concentrated on heavy civil engineering projects such as bridges, tunnels, railways and docks. Early projects included the reconstruction and extension of the City & South London Railway, the building and extension of the Central London Railway, the construction of lifts beneath St Mary Woolnoth church at Bank Underground station, the underpinning of Clifford's Tower, the reconstruction of Southwark Bridge and the widening of Blackfriars Bridge. Mott and Hay employed a young engineer called David Anderson as resident engineer for the latter project.