Little is known about what happened to Maryport after the departure of the Roman army but, like most of the coastal area of Cumbria, it would have been subject to invasion and settlement by Norse people. Illustrating this period of Nordic influence is Crosscanonby Church to the north of Maryport. This early medieval building retains a Viking Hogback grave-cover and cross-shaft.
At the time of the Norman Conquest in 1066 Maryport and the surrounding area was part of Scotland and therefore did not appear in the Domesday Book. In the Norman period the border moved around until the C12, after which Cumbria became English.
Surviving from this period is Motte Hill, the site of a C12 motte and bailey castle strategically sited on the elevated peninsula surrounded by a meander of the River Ellen close to the estuary and port. This was occupied for approximately 200 years until abandoned by the lords of the manor in favour of Netherhall by the C14.
The manor of Ellenborough, formerly called Alneburgh, was possessed by Simon de Sheftling in whose family it remained until the reign of Edward I (1272-1307), when it was purchased by the Eaglesfields. In 1528 Elizabeth, sister and co-heiress of Richard Eaglesfield of Alneburgh Hall (later Netherhall) married John Senhouse of Seascale. The Senhouse family had resided at Seascale for several generations. The younger son of John Senhouse settled at Netherhall and this became the principal family home from the mid C16 to mid C20. The Senhouse family is inextricably linked with the development of Maryport in the C18 & C19. The family had antiquarian interests and assembled the internationally important collection of Roman antiquities displayed at the Senhouse Museum (to the north of the town).
Camden, writing in 1599, after his visit to Netherhall, records: “I could not but make an honourable mention of the gentleman I just now spoke of (Mr. J. Senhouse). . . . because he has a great veneration for antiquities (wherein he is well skilled), and with great diligence preserves such inscriptions as these, which by other ignorant people in those parts are presently broke to pieces, and turned to other uses, to the great damage of these studies.”