Romney Lock is a lock on the River Thames in England near Windsor and Eton, about half a mile downstream of Windsor Bridge. It is on the Windsor side of the river next to a boatyard and adjoins Romney Island, a long strip-shaped ait in the middle of the river. The first lock was built by the Thames Navigation Commission in 1798. The weir is some distance upstream near the end of Romney Island and runs across the river to Cutlers Ait. A small 200kW hydroelectric generation station was installed in 2011 to supply electricity to Windsor Castle.