Desborough Island is a 112-acre (0.45 km2) manmade island in the River Thames on the reach above Sunbury Lock in Surrey, England. It was formed in the 1930s by the digging of a channel – the Desborough Cut – by the Thames Conservancy as a meander cutoff of narrow width on the right bank. The island and cut are named after Lord Desborough, a chairman of the Thames Conservancy.