Watching brief by C Currie of CKCA during the excavation of test pits behind the lock chamber walls, found no evidence that the concrete sides acted as a facing for earlier brick sides. Substantial horizontal timbers were found behind the concrete suggesting that these were part of a bracing structure to help support an earlier timber revetment. These also show that lining of the lock chambers was converted from timber to concrete at this site, without any intervening brick stage as previous documentary research had suggested.