Sir Walter was the second son of Sir Walter Strickland of Boynton Hall. He held high office in Oliver Cromwell's Protectorate government and went on two diplomatic missions to Holland in an effort to quell support there for KIng Charles I and his Queen Henrietta Maria. He was appointed Ambassador General to the United Provinces of the Netherlands at the then huge salary of £600 per annum. His mission in Holland was unsuccessful, but the respect he earned led to his being pardoned by King Charles II at the Restoration of the monarchy in England. The royal pardon document was found at St. Oswald's Church, Flamborough, where Walter held the manor (which he had purchased from Sir Henry Griffith of Burton Agnes in 1650). In 1661, Walter became MP for Thirsk.