Benson Lock is a lock on the River Thames in England, close to Benson, Oxfordshire but on the opposite bank of the river. The first pound lock here was built by the Thames Navigation Commission in 1788 and it was replaced by the present masonry lock in 1870. The distance between Benson Lock and Cleeve Lock downstream is 6.5 miles (10.4 km) - the longest distance between locks on the River Thames.