Thames Head is a group of seasonal springs that arise near the village of Coates in the Cotswolds, about three miles south-west of the town of Cirencester, in the county of Gloucestershire, England. The spring water comes from the limestone aquifers of the Cotswolds. One or more of these springs are traditionally identified as the source of the River Thames.
In actuality, the source of the River Thames does not have a fixed location – rather, it changes according to the level of the groundwater in the limestone. In dry periods, the groundwater level falls, causing the Thames Head springs to dry up and the river to begin lower down in its course. In wet conditions, the groundwaters rise and the river can begin at one of the Thames Head springs.
The Ordnance Survey identifies Thames Head as the source of the Thames on its maps and the UK's Environment Agency follows their precedent. However, there is also a long-standing alternative view that the real source of the Thames is on a different headstream entirely: at Seven Springs, Gloucestershire, the source of the River Churn, which is officially a tributary of the Thames that joins the Thames at Cricklade and which is longer than the course of the Thames from Thames Head to Cricklade.
Thames Head is a group of seasonal springs which, when flowing, form the headstream of the River Thames, the major river which runs through the South of England and the centre of London. Their location is in fields near the villages of Coates and Kemble, on either side of the A433 road, about three miles south-west of the town of Cirencester, in the Cotswolds, Gloucestershire.
The field to the north of the A433, Trewsbury Mead, has the highest-located springs, which tend only to flow during a wet winter. One of these springs is marked with an inscribed stone marker. Below it, the springhead itself is in a hollow that has been lined with stones.
Thames Head is 360 feet (110 m) above sea level, at grid reference ST980994.
The actual start of the River Thames changes as the level of groundwater changes. The spring known as Lyd Well, located south of the A433 (grid reference ST989984), is often where the river starts. In 2011, the lowest recorded start of the Thames was just upstream of Ashton Keynes, which is over 6 miles (10km) downstream from Thames Head.
The marker stone in Trewsbury Mead bears the inscription:
THE CONSERVATORS OF THE RIVER THAMES
THIS STONE WAS PLACED HERE TO MARK THE
SOURCE OF THE RIVER THAMES 
Thames source controversy
The claim that this site is the source of the River Thames is disputed. The Environment Agency, the Ordnance Survey and other authorities have the source of the Thames as Thames Head. Others hold that the true source of the Thames is at Seven Springs, Gloucestershire, some 11 miles (18 km) farther north, and east of Gloucester. Seven Springs is officially the source of the River Churn, which is a tributary of the Thames that joins at Cricklade. As it is further from the mouth of the Thames than Thames Head, the adoption of Seven Springs as its source would make the Thames the longest river in the UK.
|Wikimedia Commons has media related to Thames Head.|
- "Landscape around the Thames Head spring, the source of the river Thames in Gloucestershire". The National Archives. CC73/00044. Photo taken 1874, by Henry W. Taunt at Thames Head, Coates, Gloucestershire.CS1 maint: postscript (link)
- "The second spring of the Thames Head, located in Trewsbury Mead. A statue of Old Father Thames once stood in the field but was removed to Lechlade where the Thames becomes navigable to larger boats.(General view)". The National Archives. CC73/00041. Photo taken 1880, by Henry W. Taunt at Thames Head, Coates, Gloucestershire.CS1 maint: postscript (link)
- "A mole catcher at work in the field where the fourth spring of the Thames Head emerges. From here the river runs to Somerford Keynes and then on to Cricklade.(General view)". The National Archives. HT03070. Photo taken 1881, by Henry W. Taunt at Coates, Gloucestershire.CS1 maint: postscript (link)
- "View at the source of the River Thames at Thames Head showing the fourth spring and man beside the pump.(General view)". The National Archives. CC73/00534. Photo taken 1890, by Henry W. Taunt at Thames Head, Coates, GloucestershireCS1 maint: postscript (link)
- Fort, Hugh (26 April 2020). "14 amazing facts about the Thames you probably never knew". Berkshire Live. Archived from the original on 28 April 2020. Retrieved 29 November 2020.
The source of the Thames is actually in a group of springs just north of the village of Kemble in Gloucestershire. There is a stone marking the official sources at Trewsbury Mead. The catch is the spring is mostly dry. However, the Thames Head group of springs is a few hundred metres away and this is where the water flows from.
- "ABOUT COATES – Coates Parish Council". www.coatesparish.org.uk. Retrieved 28 November 2020.
- Ross, David. "Thames Head, the Source of the River Thames". Britain Express. Archived from the original on 19 February 2020. Retrieved 28 November 2020.
- Gordon, Emily (November 2011). Goody, Helen (ed.). "Achieving a healthy balance between People, Business and the Environment" (PDF). The Stripling. Upper Thames Protection Society (31): 1.
- Dorothy Hart (9 May 2004). "Seven Springs and the Churn". The-river-thames.co.uk. Retrieved 17 May 2010.
- BBC News, Gloucestershire. 15 May 2012 Could the River Thames be longer than the River Severn? by David Bailey
- Thames Pathway Ch1, Accessed 15 August 2015