This document sets out the results from an archaeological watching brief carried out at South Park Moat, Grayswood, Surrey during works to seal a leak to the dam. The dam forms part of a medieval moated site which is a Scheduled Monument (No.1012791). The results confirm the findings of previous archaeological works at the site, that the dam is principally composed of sand/sandstone, although the present works did not extend to a depth sufficient to penetrate to the buried soil beneath, observed in those earlier works. The cause of the present leaks was found to be the poor quality of the seal between the current sluice and the dam to the north. A new seal of Benonite clay was inserted, as had been done in 2004 on the south side of the sluice.