Cigar in hand…

Cigar in hand, stovepipe hat on head, this Victorian engineer drove a railway west from London on rails seven feet apart, tunnelled through Box Hill and designed a chain bridge over the Avon gorge. He also built three record-breaking steamers, the second of which still sits in a Bristol dry dock. He died in 1859. He was chief engineer of the Great Western Railway and designed the Clifton Suspension Bridge.

The answer in 21 letters