Dashwood was allied with the Tories as evidenced when he was elected a "nephew" of the Board of Brothers, the Duke of Beaufort's drinking club, in February 1710. In September of that year, Beaufort was a key figure in Dashwood's campaign at Stockbridge, a "notoriously venal borough which was accustomed to electing outsiders. Dashwood was duly returned unopposed alongside the Earl of Barrymore", a fellow member of the Board of Brothers. Dashwood did not make any significant contribution to Commons in his only Parliament. While initially he maintained the party line, he was "listed as one of the 'worthy patriots' who in the first session sought to discover the mismanagements of the previous administration."[9] On 25 January 1712, the day after the vote of censure against the Duke of Marlborough, he was one of the eight Members to receive the thanks of the Board of Brothers for their "good attendance and service" in the House. The following month he was identified as a member of the October Club, but before the Parliament was over he had broken with his party, choosing to vote against the French commerce bill on 18 June 1713.[9] "Only a few weeks before, he had presented at court an address on behalf of his constituents which gave thanks for the end of the war, but his apostasy in that division may have cost him his seat, since he did not appear at the succeeding Stockbridge election."[9]
After 1713, it appears that Dashwood did not pursue any further political activity. He acquired an estate at Heveningham, Suffolk in 1719, and, in 1732, became High Sheriff of Suffolk. In 1738, fortune was further bolstered by his brother Thomas' "bequest of 'a considerable estate'", although he sold all of his Suffolk holdings in 1745. By the time of his death in 1758, he had settled in the fashionable area of St George Hanover Square..[9]
Through his only son Samuel, he was a grandfather of Ann Catherine Dashwood (wife of political reformer John Cartwright),[13] Diana Dashwood (wife of Charles Vere Dashwood, a descendant of Sir Robert Dashwood, 1st Baronet),[14] Samuel Bateman Dashwood, Sophia Dashwood, George Bateman Dashwood, William Bateman Dashwood, and Francis Bateman Dashwood (wife of
Teresa March).[a]