Lambton Park extends along both sides of the Wear, and the present castle dates from 1820-28. Nearby is the location of the famous Lambton Worm legend. For failure to carry out the old sibyl's instructions after the slaying of the worm, nine generations of Lambtons were fated not to die in their beds.

Sir William Lambton was killed at Marston Moor while commanding the Durham Dragoons for King Charles in the English Civil War, but a parliamentary tradition grew up in the 18th century, and General John Lambton MP for Durham declined a peerage in 1793. The first Earl Lambton was John George Lambton, one of the most outstanding individuals ever produced by the county. He was an astonishing man, greatly influential in his time but scandalously neglected today, even by historians. He was proud of his wealth and position and loved to show off; his famous remark that a man could 'jog along on forty thousand a year' earned him the nickname of 'King Jog'. Yet the people regarded him as a hero and cheered his children in the streets. His son, who died of consumption, was the subject of Sir Thomas Lawrence's celebrated portrait 'The Blue Boy'. He was regarded by most of his equals as a revolutionary. As a young MP, he had the nerve to tell the House of Commons in 1821 that the majority of them were returned 'without the slightest shadow of popular delegation'. When reform came in 1832, it was Lambton who was invited to join the drafting committee of four. His nickname of 'Radical Jack' was well-earned. He married the daughter of Lord Grey, the prime minister at the time, and was himself given a peerage in 1833.
A cabinet minister and Lord Privy Seal, he might well have become prime minister himself: Instead he became ambassador to Russia and in 1828, Governor-General of Canada. It was his famous Durham Report which provided the blueprint for all British self-governing colonies and Canada became the first self-governing Dominion in the Commonwealth. Harriet Martineau, when living in Tynemouth, records that despite the outlay of prodigious labour and £10,000 of his own money in producing his great report, he still had to pay four shillings and threepence to get a copy for her! Lambton died in 1840 at the age of 48, very much beloved in the county, especially among the miners, for whom he established a benevolent association in his collieries. The Penshaw Monument, a Parthenon-like design by John and Benjamin Green of Newcastle, is his memorial, standing on the hill round which the Lambton Worm wrapped itself ten times.

Sir John Colville, whose book Those Lambtons! is a most entertaining history of the family, tells us that William Douglas-Home preferred prison to obeying a wartime order which entailed the death of innocent civilians. His Lambton mother, when Sir Alec Douglas-Home, her other son, was due to form a government in 1963, told journalists that she would have much preferred Mr Butler to be prime minister. Her brother, the fifth Lord Durham, thought the choice 'a disaster'.

Radical Jack's grand-daughter, the Duchess of Leeds, threw slices of cake on the fire every day rather than hurt the cook's feelings. This went on for years and was well-known in the kitchen. Lady Lucinda Lambton, who spent many years at the castle, has conducted television viewers round some of the architectural oddities of Britain - and along the Great North Road to visit, among much else, the strange memorial to her ancestor, Radical Jack, on Penshaw Hill.