The second was built soon afterwards, still in the 13th century. It had a stone keep, or Great Tower, in the centre of a courtyard or bailey, protected by the existing curtain wall. This keep is shown on the earliest map of Morpeth, dated 1604.
In 1271 Morpeth passed from its first owners, the de Merlays, to the Greystoke family. They had other castles, and Morpeth Castle seems to have become a centre of administration, in local government and the law, only visited occasionally by its owner. It would have been under the control of a Constable, living there with his household, and a small garrison. There was, no doubt, a Steward or Bailiff as well, with a clerk, to oversee the management of Lord Greystoke's property in the area.
It is possible that the lodging for one or these important officials was on the upper floor of the imposing new gatehouse, built by William Lord Greystoke, the Good Baron, between 1342 and 1359. On the first floor, however, there was just one large chamber, but with two doorways and, possibly, a free-standing screen in the position of the present partition. This unusual arrangement suggests that it was a Courtroom, in which justice was dispensed. The gatehouse is strangely lacking in defensive features, such as a portcullis, and this also suggests that the building was intended mainly for ceremony and show, rather than military strength.
In the early 1500s the castle was, for a short period, occupied by its owner, now the Lord Dacre. Here in 1515-16 he entertained Margaret, widowed Queen of Scotland, one of many Royal visitors to Morpeth over the centuries. His house was adorned with tapestries and there were vessels of silver to eat from. By the end of the century, however, the castle was described as "mightily decayed".
Surprisingly, the one great military event in the history of the castle was yet to come. Border raids had been an occupational hazard, but there is no record of the castle ever having been involved in serious warfare until 1644, and the Civil War. Then, in spite of grave doubts as to its strength, a Parliamentary garrison of 500 held the castle for 20 days against Montrose's Royalist force of 2,700. When they finally marched out, in full honour, it was discovered that they had only lost 23 men, as against 191 men of the besieging force.
By this time Morpeth belonged to the Howard family, who became Earls of Carlisle. For the next 200 years the castle was largely abandoned, providing a useful source of building stone. The gatehouse, however, was lived in, and seems to have been partly remodelled in the late 1600s when an attic floor was inserted. Early 19th-century engravings show it becoming more and more dilapidated. Then, in about 1860, the Earl of Carlisle repaired the gatehouse, as a home for his agent. The parapet was rebuilt and new windows were inserted. Inside, there were new partitions and stairs.
The castle resumed its position as an important building in Morpeth until its sale in 1916. In 1946 it was bought by the Borough Council and became for a while a very unusual council house. By the 1980s, expensive repairs were needed, particularly to the roof. The castle fell vacant, and quickly became derelict. A new solution for its future was urgently sought by the Borough Council. In 1988 the council granted a lease to the Landmark Trust. The restoration of Morpeth Castle was completed in the autumn of 1991, since when it has been let all year round for holidays.