Gibside is an estate in the Derwent Valley in North East England. It is between Rowlands Gill, Tyne and Wear and Burnopfield, County Durham. Gibside was previously owned by the Bowes-Lyon family. It is now a National Trust property. The main house on the estate is now a shell, although the property is most famous for its chapel. The stables, walled garden and Banqueting House are also intact.
The Blakiston family acquired the estate by marriage in about 1540. Sir William Blakiston (1562–1641) replaced the old house with a spacious mansion between 1603 and 1620. Both the Royal (King James I of England) coat of arms and the Blakiston coat of arms are seen over the entrance of the old Hall. The Gibside property came into the possession of the Bowes family in 1713; a result of the marriage between Sir William's great granddaughter, Elizabeth Blakiston, to Sir William Bowes (1657–1707) of Streatlam Castle (now demolished) in 1693.
Until 1722, the basis of the Bowes' influence was their own estate and castle of Streatlam. However after that date the acquisition through marriage of the Blakiston estate gave the Bowes family an even greater influence in the north of the county and a share in the immense wealth that was to be acquired from the coal trade. The Blakiston estate included some of the area's richest coal seams.
In 1767 the granddaughter of Sir William Bowes – the "Bowes heiress" Mary Eleanor Bowes – married John Lyon, 9th Earl of Strathmore and Kinghorne, who changed his surname to Bowes due to a provision in her father's will that any suitor had to take the family name. This was a device to continue the Bowes lineage in the absence of a male heir.