George Thomas Clark played an important role as an engineer on the project, reputedly taking the management of two divisions of the route including bridges over the River Thames at Lower Basildon and Moulsford and of Paddington Station.[7] Involvement in major earth-moving works seems to have fed Clark's interest in geology and archaeology and he, anonymously, authored two guidebooks on the railway: one illustrated with lithographs by John Cooke Bourne;[2] the other, a critique of Brunel's methods and the broad gauge.[9]