From Sir Walter Calverley Blackett, Wallington passed to the Trevelyans of Somerset, but it was not until 1846, when Walter Trevelyan and his wife Pauline preferred the 'modern' house in Northumberland that Wallington came back to life. They were a remarkable pair. Sir Walter, 19 years older than his wife, was of a serious turn of mind, interested in botany, geology, antiques, agriculture - and the temperance movement. She was artistically talented, sympathetic and attractive to men. Painters and writers came to Wallington for her patronage and indeed her own sake. Augustus Hare was served a dinner by Sir Walter consisting solely of cauliflowers and artichokes, but he too fell under the Trevelyan spell. He wrote of his visit in September 1862:

'Such a curious place this is! And such curious people! I get on better with them now, and even Sir Walter is gruffly kind and grumpily amiable. As to information, he is a perfect mine and knows every book and ballad that ever was written, every story of local interest that was ever told, every flower and fossil that ever was found... His conversation is so curious that I follow him about everywhere, and take notes under his nose, which he does not seem to mind in the least, but only says something more quaint and astonishing the next minute. Lady Trevelyan is equally unusual. She is abrupt to a degree and contradicts everything. Her little black eyes twinkling with mirth all day long, though she says she is ill and has "the most extraordinary feels"; she is "sure no one ever had such extraordinary feels as she has." She never appears to attend to her house a bit, which is like a great desert with one or two little oases in it, where by good management you may possibly make yourself comfortable.'

Pauline wrote reviews in the Edinburgh Review and The Scotsman and her guests included Pre-Raphaelite painters like Rossetti, Holman Hunt and Arthur Hughes. John Ruskin considered Wallington 'the most beautiful place possible' and it was from Wallington that he and his wife Effie set out for Scotland with the painter Millais in that fateful summer of 1853. Effie and Millais fell in love and a protracted and scandalous divorce proceedings ensued. The painted hall is the work of another painter, William Bell Scott, who worked in Newcastle for 20 years. He was greatly enamoured with Pauline, who is pictured among the women fleeing from the Danes in one of the hall paintings. Christina Rossetti was another visitor, as was the young Algernon Swinburne who, though born in London, considered Northumberland his native county.

George Otto Trevelyan (1838-1928) was a nephew of Lord Macaulay, and lived at Wallington Hall for over forty years. He was elected as Liberal M.P. for Tynemouth in 1865 and held several important political offices, including Civil Lord of the Admiralty and chief secretary for Ireland under Gladstone.

George Macaulay Trevelyan (1876-1962) was the son of George Otto and like him, belongs to the great tradition of historians in the North East. Public access to the moors and mountains was one of the many socially progressive interests of another of George Otto's sons, the heir to Wallington, Sir Charles Philips Trevelyan (1870-1958), who sat in the House of Commons for thirty years, first as a Liberal and then as a Labour M.P. He was President of the Board of Education in 1924 and again 1929-31.

C.P. Trevelyan was a prime mover in the foundation of the People's Theatre in Newcastle. In 1936 he was present at the theatre's premises in Rye Hill in Newcastle, when his friend Bernard Shaw made his final appearance in any theatre, at the age of 80. As well as his ancestors' tradition of political activity, he inherited a touch of Sir Walter's eccentricity and thought nothing of walking the moors in a state of nudity. He gave Wallington and all its principal contents to the National Trust in 1941, subject to his life interest.