Richmond Lock and Footbridge is a lock, rising and falling low-tide barrage integrating controlled sluices and pair of pedestrian bridges on the River Thames in south west London, England and is a Grade II* listed structure. It is the furthest downstream of the forty-five Thames locks and the only one owned and operated by the Port of London Authority. It was opened in 1894 and is north-west of the centre of Richmond in a semi-urban part of south-west London. Downstream are Syon Park and Kew Gardens on opposite banks. It connects the promenade at Richmond with the neighbouring district of St. Margarets on the west bank during the day and is closed at night to pedestrians – after 19:30 GMT or after 21:30 when BST is in use. At high tide the sluice gates are raised and partly hidden behind metal arches forming twin footbridges. It was built to maintain the lowest-lying head of water of the forty-five navigable reaches of the Thames above the rest of the Tideway. Below the structure for a few miles, at low tide, the navigable channel is narrow and restricts access for vessels with the greatest draft. The next major point of mooring below the lock is, accordingly, at Brentford Dock. Description The chief engineer who designed the core of the structure, F.G.M. Stoney, took out seven patents relating to sluices between 1873 and 1894. Hunt and Steward, surveyors, designed the lockhouses. Ransomes & Rapier of Ipswich designed the ironwork including the arches. The structure was built between 1891 and 1894. The structures The superstructure was built horizontally in three sections, the middle section forms the bulk and has, itself, three spans. The lock is the first section, topped by the first of five ornate metal arches which spread over the other sections. The middle section has mechanically rising-to-parapet-height sluice gates forming sheets of metals above and close to the water line which is created by these structures when lowered. The final section is a set of two facing ramps in part with canoe/boat rollers. Purpose The lock and barrages were installed in 1894 by the Thames Conservancy to maintain a broad navigable depth of water upstream of Richmond. The rising barrage ensures upstream at least of water is in the standard navigation channel (away from banks) to the next lock, Teddington, and an annual draw-off (an all-tides lifting of the sluice gates) takes