There are in fact two locks, which are some distance downstream of the original lock built in 1812. The older hand-operated one was originally built in 1856, but is now seldom used. The newer one was opened in 1927 by Lord Desborough. There is also a slide for the portage of small boats. The lock adjoins Sunbury Lock Ait.
There is more than one weir at Sunbury lock and these are some distance from the lock. The main weir is between Sunbury Lock Ait and Wheatley's Ait, which causes a strong stream in the backwater behind. There is a further weir at the upstream end of Wheatley's Ait. There is a footbridge linking the islands, but this is not open to the public.
The earliest weir was built in 1789 specifically to divert water to create a deeper channel for navigation. There were several other such weirs locally because of many shoals and flats in the Sunbury area while the river was still tidal here. The first plan for a lock was in 1805 with an ambitious lock cut. A modified scheme in 1809 resulted in the first lock, which was built several hundred yards upstream of the present locks close to the bridge and the original lock house of the same year. The lock cut was created out of an existing channel beside the island and the lock was opened in 1812 The lock had become dilapidated by 1852 and the arrival of water companies planning major water extraction from the section of the river below the lock added an incentive for rebuilding it. It was relocated to its present position with a new lock house and opened in 1856. In 1927 a second lock was added at Sunbury, which was opened by Lord Desborough, then president of the Thames Conservancy.
Access to the lock
The lock is inaccessible from the road and can be reached along the towpath from The Weir Hotel or Elmbridge Leisure Centre on the Walton on Thames side. The weir for Kayaking purposes can be reached by water from the northern bank, between Shepperton and Sunbury-on-Thames.
Reach above the lock
There is a long lock cut beside Sunbury Lock Ait to the Weir Hotel and the weir itself which is followed by Wheatley's Ait with an Environment agency working area and riverside housing on it. There is more riverside housing and a marina entrance on the way to Walton Bridge. On the Surrey side there is some open space at Elmbridge Leisure Centre, the river frontage of Walton-on-Thames with a few pubs, and a marina. After Walton Bridge the river divides between the old course which meanders through Shepperton, and the direct Desborough Cut alongside Desborough Island. Before Shepperton lock the waters rejoin to create further confusion with the River Wey, the Wey navigation and the River Bourne joining, interspersed with D'Oyly Carte Island and Hamhaugh Island. There the Shepperton to Weybridge Ferry operates just below the lock.
There are navigation transit markers on the Desborough Cut, to allow river users to check their speed.
The Thames Path continues along the Surrey bank until just before Shepperton Lock where the ferry goes across to the other side. To avoid the ferry calls for a long detour over Walton Bridge and via Shepperton.
Sports clubs on the reach
- Elmbridge Canoe Club
- Walton Rowing Club
- St George's School Boat Club
- Weybridge Rowing Club
- Weybridge Ladies Rowing Club
- Thames Valley Skiff Club
- Desborough Sailing Club
Sunbury Weir has the highest volume and fastest freestyle kayaking playspot on the River Thames. It is wide, surging and unfriendly to new or inexperienced paddlers. The eddyline is also very unstable and requires considerable effort to cross.
Public car park on Fordbridge Road, between Shepperton and Sunbury, parallel to north side of River Thames. Once parked, walk across the field, and paddle downstream to the main weir.
The weir consists of several gates which are opened according to the river levels.
Sunbury appears to work best at a certain pool level, rather than gate configuration. So it is entirely dependent on how many gates are open at the downstream weir (at Molesey Lock). This information is not normally available, so word-of-mouth reports are essential. See links before for up-to-date websites.
- Sunbury Weir will need to be on at least 1 and a 1/2 gates for usable feature, pool level depending.
- Hurley Weir needs to be on at least 3 gates for sufficient water.
Literature and the Media
- "The river is sweetly pretty there just before you come to the gates, and the backwater is charming: but don't attempt to row up it"
- Locks on the River Thames
- Rowing on the River Thames
- Kayaking and Canoeing on the River Thames
- Sailing on the River Thames
|Next lock upstream||River Thames||Next lock downstream|
4.75 km (2.95 mi) 
4.79 km (2.98 mi)
- "Environment Agency Dimensions of locks on the River Thames". web page. Environmental Agency. 8 November 2012. Retrieved 18 November 2012. Dimensions given in metres
- Fred. S. Thacker The Thames Highway: Volume II Locks and Weirs 1920 - republished 1968 David & Charles
- "Environment Agency Distances between locks on the River Thames". web page. Environmental Agency. 19 November 2012. Retrieved 22 November 2012. Distances given in km.