| Constituency | Dates |
|---|---|
| Knaresborough | 17 May 1714 – 1715, 1722 – 18 Jan. 1763 |
Slingsby was descended from Sir Henry Slingsby, M.P., who was executed in 1658 for participating in a plot against the Commonwealth Government. Returned as a Tory on his family’s interest at Knaresborough, he was defeated at the general election of 1715, but recovered his seat in 1722, voting regularly with the Opposition. In 1743 an emissary sent by the French Government to England to concert measures for a Jacobite rising combined with a French invasion next year, recommended that he should be one of a council to be set up to advise the Young Pretender on his arrival in England.1Stuart mss 254/152. He was not appointed but was one of the few to whom the military details of the proposed French landing were communicated.2AEM and D Angl. 82, ff. 62-109. He continued to represent Knaresborough without opposition till his death, 18 Jan. 1763.