The scheduled area has been extended to include the feature referred to by Cyril Fox as an 'out-work'. This west-east extension from the Dyke is unique, being the only such feature to be found along the entire length of the Dyke. It was interpreted by Fox as a possible attempt by the builders to find an alternative means of taking the Dyke proper across the river ahead.
Source: Cadw revised schedule description.

Frances Foster, RCAHMW, 22 April 2005