Before the opening of the Great Western Railway, the journey from London to Bath by mail coach took 13 hours; the railway cut the journey time to four hours – it also ruined business for the coaching inns. Their decline is the first of many changes Swift describes, including the invasion of navvies and the cutting through Sydney Gardens; but the focus of the book is Brunel and the construction of his great railway with its bridges, viaducts and the Box Tunnel.