NHER 49169 (Monument record) - Earthwork remains of a possible post mill or fortification on South Denes

October 2006. Norfolk NMP.
The earthwork remains of a possible medieval to post medieval post mill or post medieval fortification on the South Denes, Great Yarmouth (S1-S2). The site is centred on TG 5314 0394. The earthworks consist of a cross-shaped pit surrounded by a square embankment. The feature is possibly located on the site of the former harbour fort, as recorded by the Ordnance Survey. However it is possible that this positioning is not accurate. The cross-shaped pit is more likely to relate to a former post mill.

In 1928 a cross-shaped pit is visible, 4-5m across, surrounded by a square embankment, up to 2m wide and 8m long (S1). A ditch surrounds the majority of the embankment and appears to continue to the northeast and southwest of the site for a short distance, possibly suggesting that it was originally part of a larger earthwork site. The earthworks are quite dilapidated in 1928 and appear to pre-date both the World War One and Two defences on the Denes (S1). The earthworks are still discernable in 1945 (S2), however they are not as clearly visible. The site now appears to be redeveloped and it is unlikely that any of the earthworks remain.

Comparison of the location of the earthworks with the First Edition Ordnance Survey map (1879-1886) (S3) indicated that they appear to correspond with the ruins of the 1653 Harbour Fort. It therefore initially seemed possible that these earthworks may have been the fragmentary remains of this fortification. The fort had two semi-circular bastions fronting the sea and with a rectangular enclosed area backed by a small angled bastion (S4). The earthworks visible on the aerial photographs do not appear to fit into this scheme, although it is possible that it was part of an ancillary building or store. However comparison of the location of the fort on earlier maps, such as the 1832 Boundary Commission map (S5), indicate that the fort was actually further around the harbour mouth. This is also suggested by the painting of the fort done by James Stark in around 1830 (S4), which show the fort much nearer the harbour mouth. Alterations to the pier in 1832 caused a massive tidal scour, which undermined the fort, and one of the bastions fell into the sea. The fort was then demolished and materials sold off (S4). Therefore it is possible that some confusion over the location had arisen by the time the Ordnance Survey mapped the area for the first edition map in 1879-1886 (S3).

Another possibility for the earthworks is that it is the remains of a former post mill. Post mill structures often leave a characteristic cross-shaped cut, within a circular enclosure or embanked mound. From the medieval period onwards and until relatively recently the whole of the Denes and quayside has been covered with windmills, so it is possible that theses earthworks relate to a former mill site, although the location, so close to the harbour’s mouth may be unlikely.
S. Massey (NMP), 25 October 2006.