Thames Head is the site in Gloucestershire, traditionally identified as the source of the River Thames, a major river which runs through the centre of London. It is in a meadow known as Trewsbury Mead near the village of Kemble and the town of Cirencester. While the Environment Agency, the Ordnance Survey, and other authorities have the source of the Thames as Trewsbury Mead, others hold that the true source of the Thames is at Seven Springs, Gloucestershire, the source of the River Churn, which is a tributary of the Thames.