There was still work to do before going to Parliament, and Moorsom had to defend his planned route. Castleman had given a personal undertaking that the route within Southampton would be on the foreshore, across the mudlands, and would probably have much improved trade in the lower town, but the LSWR were now in control. Castleman's preferred alignment would have enabled the reclamation of a considerable area of useless tidal mud. However the Pier Commissioners demanded the use of horses, and not locomotives, throughout the quays at Southampton, and the LSWR refused to give any such undertaking, and decided upon an alternative route that ran on the landward side of the town and would require a tunnel.