A civil engineer he was introduced to Isambard Kingdom Brunel in 1834 in whose office he commenced his engineering studies, and whom he assisted in the preparation of the designs for the Monkwearmouth Docks, the Clifton and the Hungerford Suspension Bridges, and more particularly the Great Western railway, and its various branches, all the details of the surveys, calculations, &c., passing through Mr. Clarke's hands.
With the gradual extension of the Great Western Mr. Clarke was intimately connected, and he was, in 1840, placed in charge of the line from London to Swindon. In May, 1850, Mr. Clarke became the General Manager of the Great Northern railway,
Mr. Clarke was elected an Associate of the Institution of Civil Engineers on the 5th of December, 1865, and on the creation of the Engineer and Railway Volunteer Staff Corps in the same year he received Her Majesty's commission as a lieutenant-colonel in 'that corps. (John Speller)