Complex sentence: It was decided to submit their own response to the requirement, designated as the M.S.405; work on the design was headed by the firm's Engineer-in-Chief, Paul-René Gauthier.
Split into simpler sentences: It was decided to submit their own response to the requirement, designated as the M.S.405. Work on the design was headed by the firm's Engineer-in-Chief, Paul-René Gauthier.